Chapter 1
Structure and Functions of a Computer
"Hardware: the parts of a computer that can be
kicked." ~ Jeff Pesis
After completing this chapter, you will be able to:
1. Explain the importance of computer literacy.
2. Define the term computer.
3. Identify the components of a computer.
4. Compare the uses of various types of: input devices, output
devices, and storage devices.
5. Describe categories of computers and their uses.
Structure and Functions of a Computer
1
1.0 Introduction
A computer is an electronic machine designed for the storage and
processing of data. The machinery is called hardware, and this highly
sophisticated equipment needs equally sophisticated programs (called
software) to become a working computer system.
Modern society has come to depend very heavily on the use of computer
systems. Banks, businesses, government departments, industries, shops,
people at home and school all rely on computer to play a vital role in
their daily activities. These activities are centered on information.
In business, the computer system has been used a lot and replaced filing
cabinets as means of storing information, and clerical workers as a
means of processing it. By storing and processing information on a
computer system, these businesses can function more quickly and
efficiently, because information can be found and collated much faster.
Discovery Learning:
A computer was also called a data processor. Why?
1.1 Major Parts and Functions
A Computer is an electronic device that accepts input data,
processes data, stores data and produces output into useful information.
Data is a collection of raw unprocessed facts, figures and symbols.
Computers process data to create information. Information is data that is
organized, meaningful, and useful. Whereas a system is a set of
interrelated parts that performs different functions to achieve the same
desired results. A computer system is composed of Hardware and
Software.
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Structure and Functions of a Computer
Discovery Learning:
Give examples of data and information.
Hardware refers to the physical equipment, which makes up a computer
system such as monitor, keyboard, processor, printer etc. Hardware
works under the control of software. Software, refers to computer
program, a program is set of instructions, example: Spreadsheet (Excel),
Word, Database (Access) etc. The specific software needed depends on
the tasks that have to be performed.
A computer system consists of three main components or parts and each
part is responsible for the three major functions that constitute a
computer. The parts are:
Figure 1.1a Flow of information
Structure and Functions of a Computer
3
Components
Function
Input device
Put in the data
Processor
Process the data
Output device
To get the information out
Storage device
To file information for future use
Table 1.1 Components and Function
Parts of a computer system
Figure 1.1b Parts of a Computer System
Discovery Learning:
What does it mean to be computer literate?
4
Structure and Functions of a Computer
1.2 Hardware Components
1.2.1 Input Devices
The input function involves accepting data in machine-readable form and
sending it to the CPU Unit for processing. The input data may be from
other machines, devices or storage. Input can be supplied by a person, by
the environment or by another computer. Some examples of the kinds of
input a computer can process are words and symbols in a document,
numbers for a calculation, instructions for completing a process, pictures,
audio signals form a microphones and etc. An input device gathers and
translates input into machine language (a form that the computers can
process).
Device Name
Description
Used for typing commands, messages and instructions
Keyboard
and transmitting them to CPU for interpretation and
action.
Used for pointing at items displayed on the screen
Mouse
(selecting) and activating them by clicking the buttons
or icons.
Can read data off other common medium like paper
Scanners
for input into CPU for processing.
Can read data from magnetic tape, floppy and hard
Readers
disks and other storage devices for input to the CPU
for processing.
Table 1.2a Input Devices
Additional input devices include light pen, stylus, sensors, digital
cameras and graphics tablets are handy for working with graphical input.
Microphones and electronic instruments provide input capabilities for
sound and music.
Structure and Functions of a Computer
5
Input devices are of two kinds Keyboard entry and Direct entry.
Keyboard entry is when data is entered through a keyboard. A standard
keyboard is called a QWERTY keyboard because of the layout of its
keys. That is, the first six leftmost letters on the top alphabetic line of the
keyboard spell QWERTY.
Escape key – cancels a selection or a procedure
Typewriter keys
Function keys – (F1 – F12)
Numeric keypad – (enters numbers/arithmetic symbols/ control
cursors or insertion point)
e. Windows key – displays the start menu
f. Space bar – enters blank spaces between characters
g. Navigation keys – control the cursor or insertion point on the
screen
h. Multimedia control keys – controls the media player
i. Toggle keys – switches a feature on or off
j. Ctrl and Alt keys – provide additional and shortcut functions
a.
b.
c.
d.
a
j
c
h
d
f
Figure 1.2.a Standard keyboard
6
i
b
e
Structure and Functions of a Computer
g
There are a wide variety of different keyboard designs. The most
common type is Traditional keyboards which are full-sized, rigid,
rectangular keyboards that include function, navigational, and numeric
keys. Some newer keyboard designs include the following:
Flexible keyboards fold or roll up for easy packing or storage. They are
designed to provide mobile users with a full-sized keyboard with
minimal storage requirements.
Ergonomic keyboards are similar to traditional keyboards. The keyboard
arrangement, however, is not rectangular and a palm rest is provided.
They are designed specifically to alleviate wrist strain associated with
the repetitive movement of typing.
Wireless keyboards transmit input to the system unit through the air. By
eliminating connecting wires to the system unit, these keyboards provide
greater flexibility and convenience.
PDA keyboards are miniature keyboards for PDA used to send e-mail,
create documents, and play games.
Figure 1.2b Ergonomic keyboard (left) &Flexible keyboard (right)
Structure and Functions of a Computer
7
Terminal is a form of input device that consists of a keyboard, monitor
and communications link. Terminals can be either:
Dumb terminal can be used to input and receive data but it cannot
process data independently. It is used to gain access to information from
a computer usually a server.
Intelligent terminal includes the processing unit, memory and secondary
storage. It can process data independently.
Network terminal also known as a thin client or network computer, is a
low-cost alternative to an intelligent terminal.
Internet terminal also known as a web terminal provide access to the
internet and display Web pages on a standard television set.
Direct Entry does not require data to be keyed by someone. Instead the
direct entry devices create machine-readable data and feed it directly into
the CPU. This reduces the possibility of human error and is an
economical means of data entry. Direct entry devices may be categorized
into these categories.
a. Pointing devices
b. Scanning devices
c. Image capturing devices
d. Audio-input devices
Pointing device is a device with which you can control the movement of
the pointer to select items on a display screen.
Mouse is used for pointing at items displayed on the screen (selecting)
and activating them by clicking on the buttons. The mouse pointer
usually appears in the shape of an arrow. It frequently changes shape,
however, depending on the application.
Although there are several different mouse types, there are three basic
designs.
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Structure and Functions of a Computer
Name
Description
Mechanical Mouse
Is generally considered the traditional type
and the most widely used. It has a ball on the
bottom and is attached with a cord to the
system unit.
Has no moving part. It emits and senses light
to detect mouse movement. It can be used on
any surface, is more precise, and does not
require periodic cleaning.
Is a battery-powered device that typically uses
Cordless or
radio waves or infrared light waves to
wireless mouse
communicate with the system unit. These
devices eliminate the mouse cord and free up
desk space.
Table 1.2b Types of Mouse
Optical Mouse
Figure 1.2c from left to right – optical, wireless and mechanical mouse
Joystick is the most popular input device for computer games. You
control game actions by varying the pressure, speed, and direction of the
joystick
Touch screen is particular kind of monitor screen covered with plastic
layer. Behind this layer are crisscrossed invisible beams of infrared light
allowing someone to select actions and or commands by touching the
screen with a finger.
Structure and Functions of a Computer
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Figure 1.2d Joystick (left) & Touch screen (right)
Light pen is a light sensitive pen like device. The light pen is placed
against the monitor. This closes a photoelectric circuit and identifies the
spot for entering or modifying data. Engineers use light pens, for
example, designing anything from microprocessor chips to airplane
parts.
Stylus is a pen-like device commonly used with tablet PCs and PDAs. A
stylus uses pressure to draw images on a screen. A stylus interacts with
the computer through handwritten recognition software. Handwritten
recognition software translates handwritten notes into a form that the
system unit can process.
Digitizer is a device that can be used to trace or copy a drawing or
photograph. The shape is converted to digital data. A computer can then
represent the data on the screen or print it out on paper.
Figure 1.2e left to right – light pen, stylus, and tablet digitizer
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Structure and Functions of a Computer
Pen-based computing is a pen-based small computer that lets you use a
stylus to write directly on the display screen, these devices contain
software that can recognize a person‟s handwriting.
Scanning Devices are devices that use a magnetic or photo-electric
source to scan and convert images into electric signals that can be
processed by an electronic apparatus, such as a computer. Images that
can be scanned and converted include colored or black and white texts,
graphics, and pictures. Scanning device includes the following:
Optical scanner also known simply as a scanner accepts documents
consisting of text and images and converts them into machine-readable
form. There are two types of optical scanners: flatbed and portable.
o
o
Flat-bed scanner - This type of scanner operates by placing the
text or image on the scanning device and a motor-driven scanner
makes a pass or several passes over the document in order to
scan it.
Portable scanner - is typically a handheld device that slides
across the image, making direct contact.
Fax machines/facsimile transmission machine scans image of a
document and encode it as a series of instructions, representing black and
white image areas. They convert these instructions into a format to send
them electronically over telephone lines to a receiving fax machine,
which converts the signals back to an image and recreate it on paper. The
machine uses a process much like those used by photocopiers.
Bar code readers are photo electric scanners that read the bar codes or
vertical zebra stripped marks printed on a product container.
Supermarkets use a bar code called the Universal Product Code (UPC),
which identifies the product to the supermarket computer. The computer
has a description and the latest price of the product. It automatically tells
the Point of Sale (POS) terminals the price and prints the price and
product name on the receipt.
Structure and Functions of a Computer
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Figure 1.2f left to right – flat bed scanner, fax machine, barcode reader
Character and mark recognition devices are scanners that are able to
recognize special characters and marks. They are specialty devices that
are essential tools for certain applications. Three types are
Magnetic ink character recognition
(MICR) direct entry method used in
banks. This technology is used to
automatically read those futuristic
looking numbers at the bottom of
cheques. Special purpose machines
known as reader/sorter reads characters
made up of ink containing magnetized
particles.
Figure 1.2g MICR in ATM
Optical character recognition (OCR) uses special pre printed characters
which are read by a light source and changed into machine readable
code. A common OCR device is the hand-held wand reader. These are
used in department stores to read retail price tags be reflecting light on
printed charts.
Optical mark recognition (OMR) also known as mark sensing. An OMR
device senses the presence or absence of marks such as pencil marks.
Multiple answer sheet used in exam can be read using optical mark
reader. The position of the marks is compared with the stored set making
marking a very quick and accurate process.
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Structure and Functions of a Computer
Discovery Learning:
Identify how the barcode readers work?
What is a wand reader?
Image capturing devices are devices that create or capture original
images.
Digital camera is similar to traditional cameras except that images are
recorded digitally on a disk or in the camera‟s memory.
Digital video camera unlike traditional video cameras, digital video
cameras recorded digitally on a disk or in the camera‟s memory. Most
have the capability to take still images as well. WebCams (Web cameras)
are specialized digital video cameras that capture images and send them
to a computer for broadcast over the internet.
Audio – input devices allow a user to send audio signals to a computer
for processing, recording, or carrying out commands.
Voice input device converts person‟s speech into digital codes. Such
systems must be trained to the particular user‟s voice. Spoken words are
matched to patterns previously stored in a computer. Voice input systems
enable users to keep hands free for other tasks. They are becoming an
office advantage for physically challenged people. This system is also
known as speech recognition device or voice recognition system device.
The most commonly used voice input device is the microphone.
Musical instrument digital interface or MIDI is a standard that allows
musical instruments to connect to the system unit using a special MIDI
port. MIDI devices are specialized musical instruments that provide
input in the form of encoded digital signals representing musical sounds.
MIDI devices can be used create, record, and play back musical
compositions.
Structure and Functions of a Computer
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1.2.2 Output Devices
An output device is any peripheral device that converts machine-readable
information into people-readable form such as a monitor, printer, plotter
and voice output device. Output is either in Soft copy stored on any
storage device and Hard copy is printed on a paper.
Monitors
Visual Display unit (VDU) or Monitor is one of the most common
methods of output in which the information or data is displayed for
viewing by the users. The common features include resolution, dot pitch,
refresh rate and size.
CRT (cathode ray tube) is the most common type of monitor for the
office and the home. The monitors are typically placed directly on the
system unit or on the desktop. CRT offers an inexpensive and
dependable computer display. They are bulky, however, and consume a
fair amount of power.
LCD (liquid crystal display) produces an image by manipulating light
within a layer of liquid crystal cells. Modern LCD technology is compact
in size and lightweight, and provides an easy-to-read display. LCDs are
standard equipment on notebook computers. The advantages of LCD
monitors include display clarity, low radiation emission, portability, and
compactness. They are, however, more expensive than CRT monitors.
Plasma screen technology creates an on-screen image by illuminating
miniature colored fluorescent lights arrayed in a panel-like screen. The
name plasma comes from the type of gas that fills fluorescent lights and
gives them their luminescence. Like LCD screens, plasma screens are
compact, lightweight and more expensive that CRT monitors.
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Structure and Functions of a Computer
Figure 1.2h LCD flat panel monitor (left) & CRT monitor (right)
Printers
A printer is an essential peripheral device in any computer system. It
provides the output in paper form which people can take away to read,
analyze or store. There are many different types of printers available:
Impact printer‟s forms characters by some mechanical means of
hitting the paper through an inked ribbon. Impact printers can
produce carbon copies and are fairly loud, although covers are
available to muffle the noise. Impact printers can produce a
document, line or a character at a time.
Printer Category
Description
Line printers
Can produce only text, no graphics. E.g.
Daisy Wheel Printers. Used by large
computers.
Usually small printers, they can produce
graphics as well as text. There are many type,
the most common one is a Dot Matrix
printer: this creates images using a dot
pattern.
Mechanism is same as other printers. Prints a
page at a time.
Characters printers
Page printer
Table 1.2c Categories of printers
Structure and Functions of a Computer
15
Non impact printers are quiet because nothing presses on the page, a
non-impact printer cannot produce carbon copies. These printers use
latest technology and have gained popularity as with time, the prices are
decreasing and nowadays, average people are able to afford them.
Description of impact & non impact printers are given in table 1.2d.
Printer Type Description
Dot Matrix
(impact)
Laser
printers
Inkjet
printers
Thermal
printers
Uses pins to strike on a ribbon coated with ink against
a paper. Noisy but is very cheap. Uses the cheapest
ink and paper for printing and requires much less
power than other types of printers.
Work in the same manner as copy machines; a laser
beam creates electrical charges that attract toner to
form an image and transfer it to paper. These printers
come in a variety of sizes. The best printers around
yet.
Are less expensive than laser printers, quiet popular
with microcomputers. Inkjets produce higher
resolution output than dot-matrix printers. They also
come in colors. More finely as the toner is sprayed
onto the paper.
Uses heat and electricity to form characters and to
produce images on heat-sensitive paper. Uses heated
dot-matrix wires to print output on specially treated
paper. As the hot pins in a thermal print head press the
ribbon against the paper, the wax melts and the ink is
transferred to the paper.
Table 1.2d Type of impact & non impact printers
Discovery Learning:
In relation to monitors and printers, Find what the following mean:
refresh rate, vis, dpi, pixel, dot pitch, resolution, TFT and HD.
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Structure and Functions of a Computer
Figure 1.2i left to right – Dot matrix printer, mini dot matrix printer for
printing receipts for POS, dot matrix paper.
Figure 1.2j Top: ink jet printer (left) & laser printer (right)
Bottom: Thermal printers (both)
Structure and Functions of a Computer
17
Table 1.2e gives the characteristics and uses of the four types of printers
Printers
Characteristics
Use
Dot
matrix
Reliable, inexpensive, forms
text and graphics by dots, some
color printing as well
In-house business
communications, shops,
printing receipts
Ink-jet
High color quality, spray
droplets of ink on paper
Internal and external
communications,
advertising pieces and
personal printing
Laser
Very high quality, form text
quality dots, using laser beam
photocopying process.
Desktop publishing,
external document,
professional reports
Thermal
Uses heat elements on special
heat sensitive papers. It prints
more quietly and usually faster
than impact dot matrix printers.
They are also smaller, lighter
and consume less power,
making them ideal for portable
and retail applications.
Mostly used for
printing receipts in
ATMs, parking meters,
ultrasound images and
eftpos machines.
Table 1.2e Printer uses
Plotters
A plotter uses pens to draw an image on paper. Architects and engineers
who produce multicolor line drawings often use plotters. It is ideally
suited for Computer Aided Design (CAD) application.
Pen Plotter creates plots by moving a pen or pencil over a drafting paper.
These plotters are the least expensive and easiest to maintain. The major
limitation is speed and the inability to produce solid fills and shadings.
The Richter scale uses pen plotting technology to draw seismic activity.
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Structure and Functions of a Computer
Ink-jet plotter they form images
like ink jet printer by spraying
droplets of ink onto the paper.
They can produce good quality
solid-color output and are
quicker than pen plotters. The
major disadvantage of ink-jet
plotter is that the spray jets can
become clogged and require
more maintenance.
Figure 1.2k Inkjet plotter
Electrostatic plotters use electrostatic charges to create images made up
of tiny dots on specially printed paper. The image is produced when the
paper is run through the developer. They produce high-resolution images
at a much faster rate than pen or ink jet plotters.
Direct image plotters or thermal plotters creates images using heat
sensitive paper and electrically heated pins, is quite reliable and good for
high volume work. It requires expensive specially treated paper.
Voice-Output Device
This device produces sound like human
speech, but is actually prerecorded
vocalized sounds. Voice output is used
in the telephone information system,
where the requested number is reported
using a voice output system. For
example, when a student enrolls courses
using a telephone registration system, he
or she hears voice output upon your
request. Voice output is becoming
common in voice messaging systems.
Figure 1.2l Speakers
Structure and Functions of a Computer
19
Review Exercise1.2
True/False
a) Input devices translate symbols that people understand into symbols
that computer can process.
b) A plotter is a device that can be used to trace or copy a drawing or
photograph.
c) Banks use a method called magnetic-ink character recognition
(MICR) to automatically read and sort checks.
d) Laser printers are highly reliable, but the quality of their output
limits their use to rough drafts and in-house communications
e) Plotters are special-purpose drawing device.
Fill in the blank
a) ____________ machines are popular office machines that can scan
the image of a document to be sent.
b) The ____________ printer is a reliable, inexpensive printer that
forms letters by a series of small pins on a print head.
c) The ___________ printer is the most widely used.
d) ____________ a device makes sounds that resemble human speech.
e) The number of dots that form an image on a monitor or printer is
referred to as ______________
Short Answer Questions
a) What is the difference between keyboard entry and direct entry as a
form of input?
b) What is a POS terminal? What are two input devices on it that
represent the two methods of inputting data?
c) How is a dumb terminal different from an intelligent terminal?
d) What is a bar code? How are bar code read?
e) What are the differences between personal and shared lasers?
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Structure and Functions of a Computer
1.2.3 The System Unit
The main part, processing unit and
devices, of a microcomputer is a system
unit. A system unit, also known as the
system cabinet or chassis, includes a
board called a motherboard Electronic
circuitry is printed on the board and it
connects between all components of the
computer system. The motherboard is
housed within the system cabinet.
Figure 1.2m System cabinet
A system unit is made up of the following parts.







Motherboard
Microprocessor
Memory Chips
System Clock
Buses
Ports/Sockets
Expansion Slots and Cards
Discovery Learning:
Observe the system cabinet in your computer lab and notice
that at least one side cover is grid like. Explain why?
Structure and Functions of a Computer
21
Motherboard
A Motherboard or system board is
the main printed, flat circuit board in
an electronic device such as
microcomputers. The board contains
expansion slots (sockets) that accept
additional boards (expansion Cards).
In a microcomputer, the motherboard
contains the microprocessor, the
primary storage chips (or main
memory cards), the buses, and all the
chips used for controlling the
peripherals.
Figure 1.2n Motherboard
Figure 1.2o Components on the motherboard
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Structure and Functions of a Computer
Microprocessor
A silicon chip contains a CPU. In the
world of personal computers, the terms
microprocessor and CPU are used
interchangeably. At the heart of all
personal
computers
and
most
workstations sits a microprocessor.
Microprocessors also control the logic of
almost all digital devices, from clock
radios to fuel-injection systems for
automobiles.
Figure 1.2p Microprocessor
Several important lines of microcomputers use some families of
microprocessor chips. Intel and AMD are the major companies that
produce important microprocessors for IBM compatible and Macintosh
computers.
Microprocessor Capacity is the capacity of a microprocessor chip and
is represented in word sizes. A word size is the number of bits (e.g. 8, 16,
32 or 64 bits) that a CPU can process at a time.
If a word has more bits, the CPU is more powerful and faster. For
example, a 16-bit-word computer can access 2 bytes (1 byte = 8 bits) at a
time, while a 64-bit-word computer can access 8 bytes at a time.
Therefore, the 64-bit computer is faster than the 32-bit computer.
Discovery Learning:
Identify and describe the uses of microprocessors in a range of
devices? What is dual core or quad core processor?
Structure and Functions of a Computer
23
The central processing unit (CPU) is the computing part of the computer
that interprets and executes program instructions. It is also known as the
processor or the brain of the computer. In a microcomputer, the CPU
is contained on a single microprocessor chip within the system unit. The
CPU has two parts: the control unit and the arithmetic-logic unit.
Additional storage units called registers within control unit and ALU
help make processing more efficient.
Control Unit is the functional unit of the CPU that is responsible for
retrieving instructions from memory, determining their type and breaking
each instruction into a series of simple, small steps or actions. It tells the
computer system how to carry out the program instructions by directing
the movement of electronic signal between memory (which temporarily
holds data, and processed information) and the ALU. It also directs this
control signals between CPU, input, output and communication devices.
The Arithmetic Logic Unit (ALU) is the component of the CPU that is
responsible for performing arithmetic (+,-, /,*) and logic (comparisons
such as <,>, =) operations.
Memory
A memory chip is a chip that holds programs and data either temporarily
or permanently. Three major types of memory chips are RAM ROM and
CMOS.
Random access memory (RAM)
Random access memory holds the data or instructions that the CPU is
presently processing. RAM is called temporary or volatile storage
because everything in most types of RAM is lost as soon as the
microcomputer is turned off or the power disrupted.
Whenever a CPU writes data or instructions to RAM, it wipes out the
previous contents of RAM replacing it with the current content it is
processing or processed but needs to be saved.
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Structure and Functions of a Computer
Types of RAM
Description
Cache memory or
RAM cache
Improves processing by acting as a temporary
high-speed holding area between the memory
and the CPU.
Flash RAM or
flash memory
Chips can retain data even if power is disrupted.
This type of RAM is the most expensive and
used primarily for special devices such as for cell
phones, digital video cameras and portable
computers.
Virtual memory
Is storage space on your computer's hard disk
that Windows uses in conjunction with random
access memory (RAM). If your computer lacks
the random access memory (RAM) needed to run
a program or operation, Windows uses virtual
memory to compensate.
DRAM
The cheapest and slowest. DRAM uses a
transistor and capacitor (a device to store electric
charges) to store binary bit.
(Dynamic RAM)
SRAM
(Static RAM)
Faster but more expensive than DRAM. SRAM
does not use capacitors to store data and does not
need regular refreshing.
SDRAM
(Synchronous
DRAM)
The most common RAM in desktop PCs.
SDRAM uses burst of higher speed to read the
individual data bits once it has located the
memory address.
RDRAM
Uses a high speed data bus (the connecting link
to the CPU) to access memory locations.
(Rambus DRAM)
VRAM
(Video RAM)
High speed RAM used to hold graphics data
including 3D models and textures.
Table 1.2f Common types of RAM
Structure and Functions of a Computer
25
Read only memory (ROM)
A ROM chip is a memory chip that stores instructions and data
permanently. Its contents are placed into the ROM chip at the time of
manufacture and cannot be modified by the user. A CPU can read and
retrieve the instructions and data from the ROM chip, but it cannot
change the contents in ROM. ROM chips usually contain special
instructions for computer operations such as ROM BIOS. ROMs are also
called firmware. The variations on the ROM chip are as follows:
PROM (Programmable Read-Only Memory) is a permanent storage
device that becomes a read-only memory after it is written once by the
customer rather than by the chip manufacturer. For example, a software
producer can write instructions onto the PROM using special equipment.
EPROM (Erasable Programmable Read-Only Memory) is a reusable
PROM-chip that can be erased by a special ultraviolet light. EPROM
holds its content until erased and new instructions can be written on it.
EEPROM (Electrically Erasable Programmable Read-Only Memory)
contents can be erased, either within a computer or externally, by electric
power. The process usually requires more voltage than the common +5
volts used in logic circuits.
Complementary Metal Oxide Semiconductor (CMOS)
CMOS chip provides flexibility and expandability for a computer system.
It contains essential information that is required every time the computer
system is turned on. The chip supplies such information as the current
date and time, amount of RAM, type of keyboard, mouse, monitor, CPU
and disk drives used.
Primary Storage (Memory)
Primary storage (internal storage, main memory, RAM or memory) is the
computer's working storage space that holds data, instructions for
processing, and processed data (information) waiting to be sent to
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Structure and Functions of a Computer
secondary storage. Physically, primary storage is a collection of RAM
chips. The contents are held in primary storage only temporarily.
Capacity varies with different computers. Data or instructions are stored
in primary storage locations called addresses.
Figure 1.2q left to right – RAM, ROM & CMOS chips
System Clock
The clock is a device that generates periodic, accurately spaced signals
used for several purposes such as regulation of the operations of a
processor or generation of interrupts. The clock circuit uses the fixed
vibrations generated from a quartz crystal to deliver a steady stream of
pulses to the processor. The system clock controls the speed of all the
operations within a computer. The clock speed is the internal speed of a
computer and is expressed in Hertz. 33 MHz means approximately 33
million cycles per second can be processed. A computer processor's
speed is faster if it has higher clock speed. For example, a 2.5 GHz
processor is capable of processing approximately 2.5 billion instructions
per second.
Buses
A bus is a data pathway between several hardware components inside or
outside a computer. It not only connects the parts of the CPU to each
other, but also links the CPU with other important hardware. The other
important hardware includes memory, a disk control unit, a terminal
control unit, a printer control unit, and a communications control unit.
The capacity of a bus is expressed as bits. A larger capacity bus is faster
in data transfer. For example, a 32-bit bus is faster than an 8-bit bus.
Structure and Functions of a Computer
27
Discovery Learning:
Identify how storage capacity is determined and the difference
between capacities like KB, MB GB, TB, and so on…
Identify the difference between the microprocessor speeds like
MHz, GHz, THz and so on…
Ports
A port is an external connecting socket on the outside the computer. This
is a pathway into and out of the computer. A port lets users plug in
outside peripherals, such as monitors, keyboards, mouse, scanners and
printers.
Standard Ports
Serial ports are external I/O connectors used to attach modems, scanners
or other serial interface devices to the computer. The typical serial ports
use a 9-pin DB-9 or a 25-pin DB-25 connector. Serial ports transmit bits
one after another on a single communications line. Serial lines frequently
are used to link equipment that is not located close by.
Parallel ports are external I/O connectors on a computer used to hook up
printers or other parallel interface devices. The parallel port uses a DB-25
connector. This port transmits several bits simultaneously. Parallel lines
move information faster than serial lines do.
Universal serial bus (USB) ports are gradually replacing serial and
parallel ports. They are faster, and one USB port can be used to connect
several devices to the system unit.
FireWire ports also known as high performance serial bus (HPSB), are
as fast as USB 2.0 ports and provide connections to specialized FireWire
devices such as camcorders.
28
Structure and Functions of a Computer
Figure 1.2r System Unit back panel with ports
Specialized Ports
There are numerous specialty ports including MIDI, SCSI, and IrDA
ports.
Musical instrument digital interface (MIDI) ports are a special type of
serial port for connecting musical instruments like an electronic
Structure and Functions of a Computer
29
keyboard to a sound card. The sound card converts the music into a
series of digital instructions. The instructions are converted to music by a
synthesizer either located on a chip on the system board or on an
external device.
Small computer system interface (SCSI) ports are a special type of high
speed parallel port for connecting a series of input and/or output SCSI
devices to a single SCSI controller card. This arrangement allows several
devices to communicate with the system unit through a single slot on the
system board.
Infrared Data Association (IrDA) ports are also known as fast infrared
(FIR) ports. IrDA ports provide a wireless mechanism for transferring
data between devices. Instead of cables, the IrDA ports from each device
are directly aligned and infrared light waves are used to transmit data.
Open/Closed architectures
Open Architecture is a system whose specifications are made public to
encourage third-party vendors to develop add-on products for it. Most
microcomputers adopt open architecture. They allow users to expand
their systems using optional expansion boards. Closed Architecture is a
system whose technical specifications are not made public. With a
machine that has closed architecture, users cannot easily add new
peripherals.
Expansion Slots
Expansion slots are receptacles inside a system unit on which printed
circuit boards (expansion boards) are plugged into. Computer buyers
need to look at the number of expansion slots when they buy a computer,
because the number of expansion slots decides future expansion. In
microcomputers, the expansion slots are directly connected to the bus.
30
Structure and Functions of a Computer
Expansion Boards
Expansion boards are also called expansion cards, controller cards,
plug-in boards, adapter cards, or interface cards. Expansion boards are
printed circuit boards that have many electronic components including
chips. They are plugged into expansion slots. Expansion boards are
connected to peripherals through ports located on the edge of expansion
boards. Expansion boards include memory expansion cards (e.g.,
SIMM), I/O controller cards (e.g., SCSI Card), video display card, sound
cards, communications cards, etc. Look back at Figure 1.2o.
Review Exercise1.2.3
True/False
a) Hardware consists of monitor, a keyboard, and software.
b) In a microcomputer, the CPU is located on a single chip called the
microprocessor.
c) RAM temporarily stores data and a hard disk permanently stores
data.
d) Another name for the system board is the processor board.
e) Memory is also known as primary storage.
Fill in the blank
a) Data and instruction are stored in memory at locations known as
_______________.
b) _______________ memory is directly accessible above 1MB.
c) The system clock controls the ____________ of operations within a
computer.
d) A _________ communication channel between the CPU and the
memory.
e) The system clock speed is expressed in _________________.
Structure and Functions of a Computer
31
Short Answer
a) What does random access mean?
b) What does volatile mean?
c) What is the purpose of the CPU?
d) Describe the two basic components of the CPU?
e) What is the difference between open and closed architecture? Give
some examples of devices that have open and closed architecture.
1.2.4 Secondary Storage
Secondary storage, sometimes called auxiliary storage, is all data storage
that is not currently in a computer's primary storage or memory. An
additional synonym is external storage.
Secondary storage also holds data and programs. However, it stores it
permanently. That is, the data or programs remain even after the
electricity power is turned off. Secondary storage devices are located
outside of the central processing unit, although they may still be built
into the system unit cabinet. This storage device includes a hard disk,
optical disk, magnetic tape and other portable drives.
A hard disk is a magnetic disk made of metal and covered with a
magnetic recording surface. Hard disks come in removable and fixed
forms that holds from several hundred megabytes to several gigabytes.
They are tightly sealed to prevent any foreign matter from getting inside
which can cause head crash. A head crash happen when the surface of
the read/write head or particle on its surface contact the magnetic disk
surface destroying some or all of the data on the disk.
32
Structure and Functions of a Computer
Hard Disk Drive
Figure 1.2s Hard Disk Drive
Types of Hard Disks
Internal Hard Disk (Figure 1.2s) is made up of several metallic platters,
a motor, an access arm and read-write heads sealed inside a metal
container. Internal hard disks have advantages over other disks. They
have high capacity, speed and are protected inside a metal casing. The
disadvantage of internal hard disks is that they have only a fixed amount
of storage and cannot be easily removed.
External Hard-Disk Drives is not built into the system cabinet of
microcomputers. External hard disk drives are treated as peripherals.
Using external hard disk drives, we can expand the hard disk capacity
when all available drive bays are occupied.
Structure and Functions of a Computer
33
Hard Disk Cartridges have advantage being as easy to remove as a
cassette from a video cassette recorder. They give micro-computer
system fast access to very large quantities of data. Note: Hard disk has
only a fixed amount of storage and cannot be easily removed, while
cartridges are easily removable and the amount of storage available is
only limited by the amount of cartridges.
Removable Drives with Cartridges allows a new form of removable
storage. This technology combines the function of the hard disk drive
and the convenience of the hard disk cartridge. This form consists of a
removable drive and several cartridges.
Hard disk packs are removable storage devices to store massive amounts
of information. Hard-disk packs have multiple recording platters aligned
one above the other. Their capacity far exceeds the other types of hard
disks.
Figure 1.2t from left to right – hard disk pack, hard disk cartridge and
external hard drive
Optical Disks
Optical disk is a disk written and read by laser beam. This optical disk
has a great impact on today's storage technology. Optical disk does not
need to move access arms and read/write heads, because a laser beam
can be moved electronically.
34
Structure and Functions of a Computer
The capacity of the storage is considerably greater than their magnetic
disk counterparts, and optical disk storage may eventually replace all
magnetic tape and disk storage. To write data, a laser beam burns tiny
cavities into the surface of a disk to
mark bits for data. To read the data, a
laser beam scans these areas. One
important characteristic of optical
disc drives is their rotational speed.
This speed is important because it
determines how fast data can be
transferred to and from the CD. The
two most commonly used optical
discs are CD and DVD with the Bluray disc slowing emerging in the
market.
Figure 1.2u Optical disk drive
Discovery Learning:
Compare and contrast the storage capacities of the CD, DVD
and the Blu-ray Disc.
Compact Disc (CD)
A CD is the one of the most widely used optical discs which is available
in a variety of formats such as:
Read-only optical disks also known as CD-ROMs or Compact Disk
Read-Only Memory and cannot be written on. The most common
applications of CDROM are in the storage and retrieval of multimedia
images and sound along with text. It can store up to 650MB on a single
side and up to 72minutes of VHS-quality video.
Write-once and read many optical disks also called WORMs or CD-R
(CD-Recordable) and are blank disks that are recorded by the user. To
write data, a powerful beam of laser light burns tiny spots into the
Structure and Functions of a Computer
35
coating that covers the surface of these disks. Once burned in, the spots
are not erasable. To retrieve the data, a less powerful laser is used to read
the pattern of spots.
Erasable optical disk also known as CD-RW (Compact Disk rewritable)
use lasers to read and write information to and from the disk but also use
a magnetic material on the surface of the disk and a magnetic write head
to achieve eraser ability. Up to 20MB can be stored n this type of disk.
Digital Versatile Disc (DVD)
DVD discs and DVD disc drives are very similar to CDs except that
more data can be packed into the same amount of space. The DVD
drives can store 4.7 gigabytes on one side of a DVD disk – more than
seven times the capacity of a CD. Many DVD drives can store data on
both sides of the disk, thereby doubling the capacity.
Digital Versatile Disk- Read Only Memory can provide over two hours
of very high quality video and sound comparable to that found in motion
picture theaters.
Blu-ray Disc (BD)
Blu-ray Disc is an optical disc storage medium designed to supersede the
DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick,
the same size as DVDs and CDs. Blu-ray discs contain 25 GB per layer,
with dual layer discs (50 GB) being the norm for feature-length video
discs.
36
Structure and Functions of a Computer
Figure 1.2v High Density Optical Discs
Other types of Storage Devices
Solid State Storage
Solid state storage is portable, provides fast access to data, and uses very
little power, so it is an ideal solution for storing data on mobile devices
and transporting data from one device to another. It is widely used in
consumer devices, such as digital cameras, MP3 music players, notebook
computers, PDAs and cell phones.
There are several types of solid state storage devices. A USB flash drive
is a portable storage device featuring a built-in connector that plugs
directly into a computer‟s USB port. A USB flash drive requires no card
reader, making it easily transportable from one computer to another.
Flash memory cards are credit card-sized solid-state storage devices
widely used in notebook computers. Flash memory also is used in a
variety of specialized input devices to capture and transfer data to
desktop computers. Flash memory is also used to record MP3/4 music
files and to transfer those files to computers and other devices.
Structure and Functions of a Computer
37
Key chain flash memory devices are so compact that they can be
transported on a key ring or necklace. Key chain hard drives
conveniently connect directly to a computer‟s USB port to transfer files.
Compact Flash (CF) cards are about the size of a matchbook and provide
high storage capabilities and access speeds. Compact Flash cards include
a built-in controller that reads and writes data within the solid state grid.
Multimedia cards (MMC) offer solid state storage in a package about the
size of a postage stamp. Initially used in mobile phones, use of
Multimedia cards has spread to digital cameras and MP3 players.
Figure 1.2w Solid State Drives
Magnetic Tape
A magnetic tape is a tape coated with a magnetic material on which data
can be stored. This is a sequential storage device that is usually used for
a backup purpose. A magnetic tape is slower than direct access storage
such as disk, because it is sequential access storage. The biggest
advantage of magnetic tape is the cost. It is much cheaper than magnetic
disk and optical disk. An advanced tape backup technology (DAT) is
available these days.
38
Structure and Functions of a Computer
Figure 1.2x Magnetic tape inside a tape drive
Cache (Cache memory)
A cache is a specially designed buffer storage used to improve computer
performance by reducing access time. It holds instructions and data that
are likely to be needed for next operation by the processor. The cache
copies frequently accessed data and instructions from primary storage
(main memory) or secondary storage (disks).
Structure and Functions of a Computer
39
Review Exercise 1.2.4
True/False
a) The most inexpensive storage medium for the microcomputer is the
hard disk.
b) Secondary storage holds information within the CPU.
c) CD-R disks can be erased and used over and over again.
d) Hard disk packs are inside the computer system.
e) Magnetic are mostly used for backup.
Fill in the blank
a) Secondary storage is also known as ______________ memory.
b) The amount of time it takes the device to locate an item on a disk is
called ___________ time.
c) A type of storage that is volatile is called ______________.
d) A ___________ is an extremely high capacity compact disc capable
of storing 4.7GB to 17GB of data, instruction and information.
e) Data on an optical storage medium, such as a DVD is stored as a pits
and ______________.
Short Answer Questions
a)
b)
c)
d)
What is a head crash?
Describe the three types of hard disks?
Describe three ways to improve hard disk performance?
Give two reasons why the use of USB is becoming more popular
than CD ROMs.
e) What is the impact of using DVDs as storage device?
40
Structure and Functions of a Computer
1.3 Categories of Computer
There are different categories of computer in the market today. Different
types are designed for different purposes.
Microcomputer
A microcomputer is also known as personal computer or PC, are
computers mostly used in homes and for small business. A
microcomputer usually costs about $1,000 and its processor performs
about 1 billion operations per second. Microcomputers generally carry
out their own processing tasks and come in many sizes and shapes. These
are as follows:
Desktop PC sits on a desk like the ones in schools today. The display
screen is usually placed on the top of the horizontal desktop case. Of the
desktop micros, the most common ones in Fiji today are the IBM
(international
Business
machines) compatible. There
are more IBM compatible
computers around because they
are cheaper than the pure IBM
kind.
IBM
compatible
computers have the same
internal structure as pure IBM
and can run the same programs,
which can be run on pure
IBMs.
Figure 1.3a Desktop computer
Notebook computers also known as laptops, are portable, lightweight,
size of a large reference book, usually have their own carrying bags.
Structure and Functions of a Computer
41
Figure 1.3b Notebook computers
Handheld computers are the smallest and are designed to fit into the
palm of one hand. It is also known as palmtop computer.
Personal digital assistants (PDA) are the most widely used handheld
computer.
Discovery Learning:
Can notebook computers be connected
to the network? If yes, explain how?
Figure 1.3c PDA
42
Structure and Functions of a Computer
Server
A server is a hardware system dedicated to running one or more such
services as a host, to serve the needs of users of the other computers on
the network.
Servers are important components of networks. They provide shared
access to services on the network. A server is a software and hardware
package that provides access to particular services. Depending on the
computing service that it offers it could be a database server, file server,
mail server, print server, web server, or other. These servers may be
dedicated computers or one computer may provide a number of these
services. Some of the server software is specialized.
Shared access to resources and programs will require controls. It may not
be appropriate for everyone on the network to have access to all the files
on the network, for example, and many users accessing the same
database or files can pose security risks. Users need to know that
sensitive files cannot be accessed or altered by unauthorized users.
Figure 1.3d Facebook datacenter server in Prineville Oregon, USA
Structure and Functions of a Computer
43
A file server as shown in figure 1.3d provides access to disks and other
storage devices. The software will allow users to save and retrieve files
and include appropriate security mechanisms.
A print server allows anyone on the network to have access to printing
services. The software on the server allows a print job to be directed to
an appropriate printer in a format the printer can understand. Queues of
the jobs for the printer must be managed and appropriate information
provided for the users.
A mail server controls the transmission and receipt of mail. The server
will collect mail from users on the network and distribute it to others on
the network. Users can use the mail service from anywhere on the
network.
An internet server will provide many of the network functions that are
required for access to the internet.
A database server will provide access to an organization‟s database.
Supercomputers
Supercomputers (Figure 1.3f) are the largest, fastest and most expensive
types of computer. Unlike microcomputers and servers, supercomputers
are not designed to optimize processing for multiple users. Instead
supercomputers use their significant processing power to solve a few
very difficult problems such as predicting the weather, modeling nuclear
reactions and oil/space exploration. The speed of a supercomputer has
reached one quadrillion instructions per second. Supercomputers are
mostly used by researchers and scientists.
Discovery Learning:
Find out the types of servers used by organizations like USP,
Fintel, Telecom, ANZ, fmf and some other big companies in Fiji.
Also find out the storage capacities and speed of these servers.
44
Structure and Functions of a Computer
Figure 1.3e K Computer is currently world‟s fastest Supercomputer
Note: the supercomputers are continuously upgraded in the race to be the
fastest supercomputer by competing nations like USA, Japan, China and
the European Union. The Top list changes every six months at the time
of the writing of this book, the world‟s fastest supercomputer was
Japan‟s K Computer shown in Figure 1.3f. You can now check these
websites for the latest fastest supercomputer.
1. http://www.top500.org/
2. http://money.cnn.com/galleries/2011/technology/1111/gallery.faste
st_supercomputer/index.html
Year Supercomputer
Peak speed
(Rmax)
2009 Cray Jaguar
1.759 PFLOPS
DoE-Oak Ridge National
Laboratory, Tennessee, USA
2010 Tianhe-IA
2.566 PFLOPS
National Supercomputing
Center, Tianjin, China
Location
2011
Fujitsu K
computer
8.162 PFLOPS RIKEN, Kobe, Japan
2011
Fujitsu K
computer
10.51 PFLOPS RIKEN, Kobe, Japan
Table 1.3 List of Supercomputers in ascending order of speed
Structure and Functions of a Computer
45
Review Exercise 1.3
True/False
a) The term microprocessor is a synonym for the term microprocessor.
b) The mainframe computer was available before 1970.
c) Most computer included a network card designed to connect a
computer to the internet using standard telephone line
d) Supercomputer is the fastest type of computer in the world.
e) Mainframe computer are faster than microcomputers.
Short Answer Questions
a) Explain two differences between a mainframe computer and
supercomputer?
b) List two ways computers are used in special education in Fiji.
c) There are three types of computer and one of which is
supercomputer. What is a supercomputer?
d) Name the categories of computer which is mostly used by businesses
to centralize storage, process and manage large amount of data.
e) A large mainframe is generally software compatible with the smaller
computers in the same family. Explain this statement.
46
Structure and Functions of a Computer
1.4 Ergonomics
Ergonomics is the study of the relationship between people and their
working environment. While working with computers factors have to be
considered which may impact on the health of those who operate these
machines. The following factors need to be taken into account in order to
protect one‟s health when using a computer. Ergonomics study focuses
on the design of new and flexible computer systems and its environment
to suit humans.
Avoiding eyestrain and headache: Our eyes were made for most
efficient seeing at a distance. However, monitors require using the eyes
at closer range for a long time, which can create eyestrain, headaches,
and double vision. To make the computer easier for the eyes, take a 15
minutes break every hour or two. Avoid computers screens that flicker.
Keep computer screens away from windows and other sources of bright
light to minimize reflected glare on the screen. Special antiglare screen
coating and glare shields could be used. Keep everything you‟re focusing
on at about the same distance. Clean the screen of dust from time to time.
Avoiding back and neck pain: Work at monitors and keyboards that are
in improper position can result in the pains in the back and neck. To
avoid these problems, make sure equipment is adjustable and flexible.
Avoiding repetitive strain injury: Repetitive strain injury (RSI) also
called repetitive motion injury and cumulative trauma disorder is the
name given to a number of injuries. These result from fast, repetitive
work that can cause neck, wrist, hand, and arm pain. One particular type
of RSI, carpal tunnel syndrome, found among heavy computer users,
consists of damage to nerves and tendons in the hands.
Structure and Functions of a Computer
47
Figure1.4 Correct sitting posture when using a computer
Review Exercise 1.4
Fill in the blank
a) The new word ____________ is used to describe harmful stress
associated with computer use.
b) Computer ____________ are guidelines for the morally acceptable
use of computer in our society.
c) Keep computer screens away from windows and other sources of
bright light to minimize reflected _________ on the screen.
d) ________________ emissions can travel through a person‟s body.
e) A repetitive strain injury that causes damage to nerves and tendons
in the hands is due to __________.
Short Answer Questions
a) What is ergonomics?
b) Why ergonomics is important?
48
Structure and Functions of a Computer
c) State three things a computer user could do to avoid eyestrain and
headache.
d) Define the phrase “Repetitive strain injury”.
e) Discuss some of the most significant physical concerns created by
frequent computer use and how they can be avoided.
1.5 Summary
1. A computer is an electronic machine that operates under the control
of instructions stored in its own memory.
2. Computer accepts data (input), manipulate the data according to
specific rules (process), produce results (output), and store the results
for future use (storage).
3. Data is a collection of unorganized facts, figures, and symbols.
4. Computers process data to create information. Information is data
that is organized, meaningful, and useful.
5. Data entered into a computer is called input. The processed results
are called output.
6. The cycle of input, process, output, and storage is called the
information cycle.
7. Hardware is the physical part of the computer system.
8. Supercomputer, mainframe, server and microcomputer are categories
of computers. Microcomputers can be desktop, notebook (laptop),
tablet Pc, or handheld (palm). PDAs are the most widely used
handheld computer.
9. The system unit, sometimes called a chassis contains the electronic
circuitry, including the microprocessor and memory (primary
storage, random access memory [RAM], temporary storage).
10. Input/output devices are translators for humans and computers. Input
devices include the keyboard and mouse. Output devices include
monitors and printers.
11. Secondary storage holds data and programs. A storage device
records and retrieves data, information, and instructions to and from
Structure and Functions of a Computer
49
storage medium. Common storage devices are a hard disks, optical
disks (CD, DVD), USB flash dive and tapes.
12. Ergonomics is the study of human factors related to things people
use, including computers.
Key Terms
adapter
adapter card
data-processor
arithmetic operation
binary system
bit
bus
bus line
byte
cache memory
chassis
chip
clock speed
control unit
desktop
expansion card
50
ergonomics
fireWire port
firmware
gigahertz
graphics card
integrated circuit
interface card
laptop computer
main board
memory
microprocessor
motherboard
MIDI
nonvolatile memory
parallel port
Petaflops
port
RAM
RAM cache
ROM
semiconductor
serial port
silicon chip
slot
socket
sound card
synthesizer
system board
system clock
system unit
supercomputer
volatile storage
Structure and Functions of a Computer
Review Questions – Multiple Choice
1) The term “information” is frequently used in computing to refer to
a. the input to the computer.
b. the process of computation.
c. unprocessed facts and figures.
d. facts that have been processed into a more usable form.
2) Which phrases describes a feature of the CPU?
a. it processes the data in the computer
b. a circuit board
c. a microprocessor
d. a series of chips on a board
3) Which of the following chips contains information that is required
every time the computer system is turned on?
a. ALU
c. RAM
b. ROM
d. CMOS
4) What is the main function of RAM?
a. to process data
b. to make copies of programs
c. to be a series of chips on a board
d. to hold data while it is being processed by the CPU
5) Which of the following is not classified as an output device?
a. visual display unit
c. printer
b. scanner
d. plotter
6) Which of the following device is not a pointing device?
a. mouse
c. keyboard
b. trackball
d. touchpad
7) Which of the following hardware is responsible for the clock speed
of the computer system?
Structure and Functions of a Computer
51
a. hard disk
b. microprocessor
c. CD-ROM
d. motherboard
8) Another name for primary storage is
a. RAM
c. ROM
b. REM
d. CD ROM
9) Which of the terms below represents 1000 000 000?
a. Kilobyte
c. Gigabyte
b. Terabyte
d. megabyte
10) Which of the following types of error occurs as a result of wrong
input or misspelling?
a. input error
c. content error
b. syntax error
d. software error
11) An example of a non-impact printer is a
a. line printer
c. thermal printer
b. dot matrix
d. chain printer
12) Which of the following device is used to produce a hard copy?
a. CD-ROM
c. Printer
b. Hard disk
d. Monitor
13) Pentium 4 is an example of a
a. printer.
b. scanner.
c. processor.
d. compiler.
14) Which of the following chips contains information that is required
every time the computer system is turned on?
a. ALU
c. RAM
b. ROM
d. CMOS
15) A user plans to run multiple tasks simultaneously on a computer.
Which computer component is essential to accomplish this?
a. NIC
c. video card
b. RAM
d. sound card
52
Structure and Functions of a Computer
16) High capacity computers used primarily for research purposes are
a. microcomputer.
c. supercomputer.
b. mainframe.
d. laptop computer.
17) Keyboard keys, such as caps lock, that turns a feature on or off is
called a ________ key.
a. power
c. control
b. toggle
d. function
18) A hard disk stores which of the following?
a. software programs permanently
b. software temporary
c. data files temporary
d. data files permanently
Review Questions – Short Answers
1) Describe the functions of the three main components of a computer
system.
2) Identify the most commonly use input, output and storage devices.
3) What is the difference between memory and secondary storage?
4) Many people use microcomputers for personal and business users.
Give two characteristics of microcomputers.
5) Why it is important for a large organization to have an unlimited
power supply unit and a surge protector in its computer system?
6) What are the four commonly used units of measurement to describe
memory capacity?
7) How are CD-Rs and CD-RWs different?
8) Describe the four most widely used ports?
9) Name four expansion boards.
10) What kind of activities can you perform to avoid computer-related
eyestrain, headaches, and back and neck pain?
Structure and Functions of a Computer
53
Additional Readings
Timothy J. O‟Leary & Linda I. O‟Leary, Computing Essentials 2007:
Complete Edition, McGraw-Hill Irwin, ISBN 978-0-07-351667-7
June Jamrich Parsons & Dan Oja, New Perspectives Introductory
Computer Concepts 8th Edition, Thomson Course Technology
54
Structure and Functions of a Computer
Chapter 2
Software
"Hardware: the parts of a computer that can be
kicked." ~ Jeff Pesis
After completing this chapter, you will be able to:
1. Describe the difference between system software and application
software.
2. Discuss the various type of system software.
3. Understand how system software interacts with application software.
Software
55
2.0 Introduction to Software
The software is a series of instructions or a special program that
performs a particular task and is recorded in some form on a computer
disk. Simply, the software is an abstract collection of instructions for
computers to perform specific tasks. It is also referred to as a program or
software program. Computer software has two major categories. It is
typically classified into system software and application software as
shown in Figure 2.0 below.
Software
System
Software
Application
Software
Operating
System
General Purpose
Device Driver
Special Purpose
Utility
Language
Translator
Figure 2.0 Categories of Software
56
Software
2.1 System Software
System software is a set of programs that manage or control a
computer‟s resources. System software acts as the interface between the
user, the application software, and the computer‟s hardware. System
software is made up of four control programs which include the
following:
Operating systems – coordinate computer resources, provide an interface
between the users and the computer and run applications.
Utilities – also known as service program, perform specific tasks related
to managing computer resources.
Device drivers – are specialized programs that allow particular input,
output or communication devices to communicate with the rest of the
computer system.
Language translators – convert the programming instructions written by
programmers into a language that computers understand and process.
Figure 2.1 Using software (Internet Explorer)
Software
57
2.1.1 Operating System (OS)
An OS manages the overall operation of the computer system. It is a set
of programs that instructs and controls the hardware functions of the
computer system. Operating system software interacts between
applications software and the computer hardware.
The three main functions of an OS include:



58
The provision of the user interface that allows users to interact with
the computer systems for example Microsoft Windows provides
menus, toolbars, dialog boxes and icons that are used for a variety of
tasks.
Running applications. In a multitasking operating system where
multiple programs can be running at the same time, the operating
system determines which applications should run in what order and
how much time should be allowed for each application before giving
another application a turn.
Managing internal resources. It manages the sharing of internal
memory among multiple applications. It handles and monitors input
and output to and from attached hardware devices, such as hard
disks, printers, and dial-up ports. It sends messages to each
application or interactive user (or to a system operator) about the
status of operation and any errors that may have occurred. It can
offload the management of what are called batch jobs (for example,
printing) so that the initiating application is freed from this work. On
computers that can provide parallel processing, an operating system
can manage how to divide the program so that it runs on more than
one processor at a time. File management including the creation,
deletion, copying, naming and storing of files. Navigation through
disks, folders and files and switching between applications. Printing
and installing printers. Font management and use. Control the
display of the monitor, including the resolution and size and starting,
restarting and shutting down the computer and networking.
Software
Operating System Features
Booting the Operating System means turning on the Computer and
having the Operating System loaded. There are two types of booting.
1. Cold Booting
2. Warm Booting
Cold Booting is switching the computer on from the power source.
Warm Booting is restarting the computer either by pressing the reset
button on the system unit or by pressing Ctrl + Alt + Delete or by
selecting restart option from the start menu.
Users interact with the operating systems through either a command line
interface (CLI) or graphical user interface (GUI). Most provide a place,
called the desktop, which provides mean of access to computer
resources. Operating systems interfaces have several features in common
with application programs as shown in the table below.
Features
Function
Icons
Graphics representations for a program or function.
Pointer
Controlled by a mouse and changes shape depending
upon its current function.
Windows
Rectangular areas for displaying information and
running programs.
Menus
Provide a list of options or commands.
Dialog boxes
Provide information or request input.
Help
Provides online assistance for operating system
functions and procedures.
Command line
Prompts users to enter command to perform an action.
Table 2.1.1a Operating System Features
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59
Menus
Desktop
Folder
Icons
File
Figure 2.1.1a Desktop GUI
Command dir
entered at the prompt
Figure 2.1.1b Command line interface
Categories of Operating System
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Software
The three basic categories of operating system are stand-alone, network
and embedded.
Categories
Function
Examples
Stand-alone
operating
systems
It is a complete operating
system that works on
desktop
or
notebook
computer. Some stand-alone
operating systems, called
client operating systems,
also work in conjunction
with a network operating
system.
Windows 3.x, Windows
95, Windows NT,
Windows 98, Windows
2000 Professional,
Windows XP , Windows
Vista, Window 7, Mac
OS X, UNIX, Linux
Network
operating
systems
(NOS)
Are used to control and
coordinate computer that are
networked
or
linked
together.
Netware, Windows NT
Server, Windows 2000
Server, Windows NET
Server, UNIX, Linux,
Solaris, Cisco IOS,
JuNOS.
Embedded
operating
systems
Are used for handheld
computers
and
small
devices like PDAs and
Mobile phones.
Windows CE, Pocket PC
2002, Palm OS,
Symbian, Android,
Apple iphone,
Blackberry.
Table 2.1.1b OS categories
Discovery Learning:
Compare and contrast Windows and Macintosh operating system?
Find different versions of Mac OS and Linux OS and show the
evolution of Windows.
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2.1.2 Utilities
A utility program is a type of system software that performs a specific
task, usually related to managing a computer, its devices, or its program.
In simple terms it performs the house keeping functions of the computer
system. There are many types of utilities available and some common
ones are shown in Table 2.1.2b below.
Utility Program
Troubleshooting or
diagnostic program
Antivirus program
Function
A program that recognizes and correct
problems, ideally before they become serious.
Is a program that guard your computer system
against viruses or other damaging programs
that can invade your computer system.
Uninstall program
A program that allow you to safely and
completely remove unneeded programs and
related files from your hard disk.
Backup program
A program that make copies of files to be used
in case the originals are lost or damage.
File
compression A program that reduces the size of files so they
programs
require less storage space and can be sent more
efficiently over the internet.
Disk defragmenter
A utility program that locates and eliminates
unnecessary fragments and rearranges files and
unused disk space to optimize operations.
Table 2.1.2b Utility programs
Windows utilities
The windows operating systems are accompanied by several utility
programs as shown in Figure 2.1.2b step number 5.
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Discovery Learning:
Describe each of the Utilities given in Figure 2.1.2b step 5.
3
4
2
5
1
Figure 2.1.2b Accessing Windows XP utilities
Utility Suites
Utility suites combine several programs into one package. Buying the
packages is less expensive than buying the programs separately. The
three best-known utility suites are McAfee Office, Norton SystemWorks, and V Communications System Suite. These suites provide a
variety of utilities, including programs that will protect your system from
dangerous programs called computer viruses.
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Discovery Learning:
Describe how to keep the anti-virus software up-to-date.
2.1.3 Device Drivers
On installing components like sound cards, modem, mouse or printer,
special software called device driver is needed. Device driver is a
program that provides the interface between the application software,
operating system and hardware device. Each time the computer started,
the operating system loads all of the device drivers into the computer‟s
memory.
Whenever a new device is added or installed into the computer system, a
new device driver must be installed before the device can be used.
However, the latest operating systems come with most device drivers
preinstalled so all you have to do is plug in the device and use it. These
devices are now called plug n play devices for example mouse,
keyboard, digital cameras, flash drives and some printers.
Discovery Learning:
Name some plug n play devices that can be configured
automatically with either Window XP, Vista or 7 or any other OS
you are using.
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2.1.4 Language Translators
Language translators are programs that convert programs written
in high level programming language (described in detail in chapter
6) into machine language. Since the CPU can process only 0‟s and
1‟s everything task that we perform on the computer must be
converted into machine language (0‟s and 1‟s). Some examples of
language translators are compilers, interpreters and assemblers.
Note: do not confuse yourself with the other language translator
programs that are available which simple changes one spoken
language into another for example, English to Hindi.
Review Exercise 2.1
True or False
a) One computer can only run one kind of system software.
b) Virtual memory increases the amount of memory available to run
application programs.
c) Macintosh computers are designed to use the Pentium
microprocessor.
d) The operating system Linux is the most popular with graphic
designers and those who work in multimedia.
e) Application software allows computer to interact with the user,
applications and hardware.
Short Answer Questions
a)
b)
c)
d)
Why is a graphical user interface described as user-friendly?
What is a network operating system?
Describe at least three utility programs?
What is meant by multitasking?
2.2 Application Software
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65
Applications software is created to perform either specific or general
task which is not related to the computer system itself. Application
software can be bought off-the-shelf. There are two broad categories of
application software: special-purpose and general-purpose (refer to
Figure 2.0). Special-purpose programs are designed to perform specific
tasks for example inventory, payroll, accounting, point of sales, virtual
reality, artificial intelligence and games. This software is in most cases
customized to suit a particular business need. General-purpose
programs are designed to be used by many people to do the most
common kinds of tasks such as typing, preparing budgets, presentations
and small databases. This is why they are also known as basic
application. Word processors, spreadsheets, database management
system and presentation graphics are general-purpose applications.
Figure 2.2a Features of application software
Common features of application software
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Software
Feature
Description
Tabs
Presents tools/buttons available for selection
from the ribbon.
Shortcut keys
Special-purpose
commands.
Ribbon
Presents graphic objects/buttons for commands
Help
Presents explanations of various commands.
Dialog Box
Used to specify additional command options.
Insertion Point
Shows where data can be entered.
Scroll Bars
Used to display additional information.
Quick Access
Tools that are frequently used can be set here. Eg
Save, undo, print and print preview.
keys
for
frequently
used
Groups
Provide categorized tools options under specific
headings.
Table 2.2a Features of application software
WYSIWYG: stands for “What You See Is What You Get”. This means that
the image on the screen display looks the same as the final printed
document. The WYSIWYG feature allows the user to preview the
document‟s appearance before it is printed out.
2.2.1 Word Processing
Word processing software is used to create, edit, save and print
documents. Word processing software creates text-based documents such
as reports, letters and memos. Word processors are one of the most
flexible and widely used software tools. All types of people and
organization use word processors to create personalized Web pages. The
three most widely used word processing programs are Microsoft Word,
Corel WordPerfect and Lotus Word Pro.
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Some important features of word processing are given in Table 2.2.1b.
Editing Features
Feature
Description
Word wrap
Automatically moves the word to the next
line once the current line is full. To begin a
new paragraph or leave a blank line, you
press the Enter key.
Spelling and
Grammar
Spelling can be checked by running a
spelling checker program. Incorrectly
spelled words are identified and alternative
spelling suggested. In a similar manner,
grammar checkers can be run that will
identify poor wording, excessive long
sentences, and incorrect grammar.
Thesaurus
Enables you to quickly find the right word or
an alternative word with similar meaning.
Find and
Replace
You can quickly locate any character, word,
or phrase in your document using the search
or find commands.
Merge
Mails merge or form letter features allows
you to merge different names and addresses.
Reference
Tables contents, footnotes, end notes,
indexes, page numbers, bulleted lists etc.
Cut, delete, copy, undo, redo and paste
options.
Table 2.2.1b Features of word processing
Clipboard
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Software
Formatting Features
Feature
Description
Paragraph
Numbering,
bullet
points,
indentation, alignment, line/character
spacing and borders & shading
allows better organization of the
contents in a document.
Font
Type, color, size, bold, italics,
underline and change case allow
enhancing the appearance of the
contents of the document.
Styles
Allow contents to be organized
according the heading, sub headings
and captions.
Tables
Text documents often include both
text and numbers, This type of
information can be displayed as a
table in row-and-column format
Hypertext link
Can be created to cross-reference
information within the current
document and between other files
including WWW.
Illustrations/Graphics Objects such as lines and shapes can
be inserted and modified.
Many word processors are including
features that allow you to create and
edit documents to be displayed on
the web.
Table 2.2.1b Features of word processing cont‟d
Internet publishing
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2.2.2 Spreadsheet
A spreadsheet is an electronic worksheet used to organize and
manipulate numbers and display options for “What-if” analysis. It
enables one to manipulate figures and texts in columns and rows and
perform calculations using formulas. The columns are identified by
letters and rows are identified by numbers. The intersection of row and
column creates a cell. For example, the cell A10 is formed by the
intersection of column A and row 10. Thus spreadsheet programs
organize, manipulate and graph numeric information. The three most
widely used spreadsheet programs are Microsoft Excel, Corel Quattro
Pro and Lotus 1-2-3.
Some common features of spreadsheet programs include the following.
Formatting cells
The same font and paragraph formatting features can be applied to the
contents of a cell as in a word processor. Labels are often used to identify
information in a worksheet. Usually a label is a word or symbol, such as
hash sign (#). A number in a cell is called a value. Labels and values can
be displayed or formatted in different ways. For example, a label can be
centered in the cell or positioned to the left or right or indented. A value
can be displayed to show decimal places, dollars, or percent. The number
of decimal positions (if any) can be altered, and the width of columns
can be adjusted.
Formulas and Functions (main attribute of a spreadsheet)
Formulas are instruction for calculations. It is defined by the user and
usually comprises of arithmetic operations (+,*,-,/) with cell references.
For example: to add cells C6, D6, E6 & F6 as shown in Figure 2.2.2a,
the user defined formula written in cell G6 would be = C6+D6+E6+F6.
Functions are prewritten formulas that perform calculations
automatically. For example to perform the same addition, the function to
be used in cell G6 would be = SUM(C6:G6).
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Software
Row numbers
Column
letters
Range from
G6 to G9
Cell
Label
Value calculated
using the function
=Average(F6:F16)
Figure 2.2.2a worksheet
A range is a series of continuous cells. For example the cell G6 contains
the function =SUM(C6:F6), which adds the values from cells C6, D6, E6
and F6. The sum of the values in this range is displayed in cell G6.
Analytical graphs or charts are visual representations of data in a
worksheet. You can easily create graphs in a spreadsheet program by
selecting the cells containing the data to be graphed and then selecting
the type of chart to display. If you change one or more numbers in your
spreadsheet, all related formulas will automatically recalculate and charts
will be automatically adjusted. Recalculation is one of the most
important features of spreadsheet.
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Figure 2.2.2b Assessment result Chart
What-if analysis lets you change one or more values in your
spreadsheet, all related formulas will recalculate automatically. Thus
you can substitute one value for another in a cell and observe the effect
on other related cells in the spreadsheet.
2.2.3 Database
A database is a program, which is used for computerized record keeping.
It provides a place to store information and a way to organize data so that
it can be accessed in an organized and timely manner. A database
manager or database management system (DBMS) is a software
package used to set up, or structure a database. It also used to retrieve
information from a database.
Data is organized into tables. Each table is made up of rows called
records and columns called fields. Each record contains fields of
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Software
information about some specific item. Some of the database programs
include Microsoft Access, Corel Paradox, Lotus Approach, dBase IV.
Some features of database are as follows:
Locate and Display
A basic feature of all database programs is the capability to quickly
locate or find records in the database. Easier way to locate information is
to apply a filter to the database. A filter displays the subset of records
that meet certain conditions or criteria. The main method of locating
specific kind of data for a data from a database is to create a query. A
query locates the specified records and displays only selected fields.
Sorting
Database administrators make it easy to change the order of records in a
file. Normally, records are displayed in the order they are entered or by
key field such as social security number. Rearranging or sorting of
records is a common feature utilized by database administrators.
2.2.4 Presentation Graphics
A presentation graphics program can display numeric data in a visual
format for analysis and presentation purposes. These programs are often
used by marketing or sales people as well as many others. Most
commonly used presentation graphics programs are Microsoft
PowerPoint, Corel Presentation and Lotus Freelance Graphics.
Features that are common to most presentation graphics include the
following:
Most programs include features that help you organize the content of
your presentation such design layout and schemes that includes
preformatted text for many different types of presentations from selling a
product to reporting on progress.
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Professionally designed templates or models are provided. They include
selected combination of text layouts with features such as title placement
and size. Additionally, various bullet styles, background colors, patterns,
borders and other enhancements are provided.
Animations include special visual and sound effects. These effects
include blinking text and transitions between topics. You can insert audio
and video clips that play automatically or when selected. You can even
record your own voice to provide a narration to accompany a slide show.
2.2.5 Integrated packages and Software suites
An integrated package is a single program, which combines two or more
applications programs. An integrated package provides the functionality
of a word processor, spreadsheet, database and more. An integrated
package usually shares a common user interface and you can switch from
one application to another and cut or copy data from one to another.
The primary disadvantage of an integrated package is that the
capabilities of each function (such as word processing) are not as
extensive as in the specialized programs (such as Microsoft Word). The
primary advantage is that the cost of an integrated package is much less
than the cost of purchasing a word processor, spreadsheet and database.
The most widely used integrated package is Microsoft Works.
A software suite is a collection of separate application programs bundle
together and sold as a group. The most popular software suite is
Microsoft Office, which comes in different version.
Discovery Learning:
Give more examples of integrated packages and software suites.
Basic Applications
74
Software
Word processors
Spreadsheets
Database Managers
Presentation graphics
Integrated packages
Software suites
Microsoft Word, Lotus Word Pro, Corel
WordPerfect
Microsoft Excel, Corel Quattro Pro,
Lotus 1-2-3
Microsoft Access, Corel Paradox, Lotus
Approach
Microsoft
PowerPoint,
Corel
Presentations, Lotus Freehand
Microsoft Works, Lotus Works
Microsoft Office 2007/2010, Open Office
Table 2.2.5 Basic Applications
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75
2.3 Advanced Application
Advanced applications include graphics programs, audio and video,
multimedia, Web authoring and artificial intelligence and virtual reality.
Graphics programs
Advanced graphics programs are used by professionals in graphic arts.
Three types are desktop publishers, image editors, and illustration
programs.
Desktop publishing programs allow one to mix text and graphics to
create publications of professional quality. While word processors focus
on creating text and have the ability combine text and graphics, desktop
publishers focus on page design and layout and provide greater
flexibility. Desktop publishing programs are widely used by graphic
artists to create brochures, newsletters, newspapers and textbooks.
Popular desktop publishing programs include Adobe FrameMaker,
Adobe PageMaker, Corel Ventura, and QuarkXPress.
Image editors, also known as paint programs, are used to create and to
modify bitmap images files. In a bitmap file, the image is made up of
thousands of dots or pixels to represent images. Popular professional
image editor programs include Adobe Photoshop, Corel PhotoPaint, and
Paint Shop Pro.
Illustration programs, also known as draw programs, are used to
modify vector images. In a vector file, the image is composed of a
collection of objects such as lines, rectangles and ovals. A vector file
contains all the shapes, colors, and starting and ending points necessary
to recreate the image.
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Graphic suites
Graphics suites are the bundling of the separate graphics programs as a
group. The advantage of the graphics suites is that a large variety of
graphics programs can be purchased at a lower cost.
Audio and Video
Using audio and video editing software enables user to compile movies.
Video editing software allows one to reorganize, add effects and more to
the digital video footage. Audio editing software allows user to create
and edit audio clips. Most audio editing software has features that allow
you to add audio effects, like filters, to your tracks.
Multimedia
Multimedia also called hypermedia is the integration of all sorts of
media into one form of presentation. The media may include video,
music, voice, graphics, and text. An essential and unique feature of
multimedia is user participation or interactively.
Web Authoring
Web authoring programs are typically used to create sophisticated
commercial sites. Also known as Web page editors and HTML editors,
these programs provide support for web sites design and HTML coding.
Widely used authoring programs include Macromedia, Dreamweaver,
NetObjects Fusion and Microsoft FrontPage.
Discovery Learning:
Give an example of each of the graphics programs.
Artificial intelligence (AI)
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77
The field of computer science known as artificial intelligence attempts to
develop computer systems that can mimic or simulate human senses,
thought processes and actions. These include reasoning, learning from
past actions and using senses such as vision and touch.
Three areas which human talents and abilities have been enhanced with
computerized intelligence: robotics, knowledge-based systems, and
virtual reality.
Robots are computer-controlled machines that mimic the motor activities
of humans and some are used for household activities, entertainment
purposes, while most are used in factories and hazardous environment to
handle dangerous, repetitive tasks with high degree of precision.
Knowledge-based systems, also known as expert systems, are computer
programs that provide advice to decision makers who would otherwise
rely on human experts. These expert systems use knowledge bases that
contain specific facts, rules to relate these facts, and user input to
formulate recommendations and decisions. Expert systems have been
developed in areas such as medicine, geology, architecture, military
science, financial analysis and nature.
Virtual reality incorporates interactive sensory equipment (headgear and
gloves) allowing users to experience alternative realities generated in 3D by a computer, thus imitating the physical world. The headgear has
earphones and three-dimensional stereoscopic screens. The gloves have
sensors that collect data about your hand movement. Coupled with
software, this interactive sensory equipment lets you immerse in a
computer-generated world.
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2.4 Summary
1. Software, also called a computer program, is the series of
instructions that tells the hardware of a computer what to do.
2. System software controls the operations of the computer and its
devices and serves as the interface between a user and computer
hardware.
3. System software consists of a variety of programs including:
operating system which contains instructions that coordinate the
activities of hardware devices, utility program, which performs
specific tasks usually related to managing a computer, device drivers
are specialized programs to allow input and output devices to
communicate with the rest of the computer system.
4. Application software are program which are written for specific and
general tasks which are not related to the computer system itself.
Contrast must be drawn between application software and operating
system software.
5. There are two broad categories of application software: and generalpurpose programs and special-purpose programs.
6. General-purpose applications are widely used in nearly all career
areas. Programs include word processing documents, spreadsheets,
databases, or presentation graphics.
7. Specialized (special purpose) applications focus on specific
disciplines and occupations. These programs include graphics, audio,
video, multimedia, web authoring and artificial intelligence
programs.
Key Terms
Software
79
application software
booting
dialog box
general-purpose application
icons
Macintosh operating system
Multiprogramming
network operating system
presentation file
service program
special-purpose application
systems
utility program
warm boot
basic application
device driver
embedded operating system
help
language translator
menus
multitasking
operating system
program
software
standalone operating system
system software
virtual memory
windows
Review Questions – Multiple Choice
1. The Operating system that is widely used in Fiji is
a. Windows XP
b. Windows 7
c. Windows 2000
d. Windows 98
2. An embedded operating system usually resides on a
a. hard disk
c. ROM chip
b. RAM chip
d. removable disk
3. The ability to have a number of applications running at the same
time:
a. GUI
c. integrated
b. networking
d. multitasking
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4. A _______________ combines several utility programs into a single
package.
a. utility service
c. disk scanner
b. zipped file
d. utility suite
5. When using a word processor, the command to reinsert text into a
document is
a. cut
c. copy
b. move
d. paste
6. A program that enables you to quickly find the right word or an
alternative word with a similar meaning is
a. thesaurus
b. spelling checkers
c. grammar checkers
d. search and replace
7. One example of an expert system is
a. CAD/CAM
c. Windows 2000
b. the personal computer
d. troubleshooting
8. In MS Word, which of the following buttons would align text evenly
on both the left and right margins?
a. centre button
c. justify button
b. align left button
d. align right button
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81
9. Database management system are c comprised of tables that are
made up of rows called _____________ and columns called
____________
a. records, fields
c. address, fields
b. fields, records
d. records, ranges
10. Security personnel use ____________ to locate and disarm explosive
devices.
a. mobile robots
c. system robots
b. industrial robots
d. perception robots
11. Which of the following terms best describes people who gain
unauthorized access to computers for the purpose of doing damage?
a. hackers
c. crackers
b. criminals
d. employees
12. A program that fills a computer system with self-replicating
information thus clogging the system is called a
a. Bug
c. damage
b. worm
d. virus
13. These programs guard your computer against malicious programs
that may invade your computer system?
a. file compression program
b. backup program
c. antivirus program
d. troubleshooting program
14. Every time the computer system is started, the operating system
loads these into memory
a. driver updates
c. device managers
b. device drivers
d. windows updates
15. The software that would be most suitable to include special visual,
sound effects and audio as well as video clips is
a. MS-Excel
c. MS-Word
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b. MS-Powerpoint
d. Desktop Publishing
16. The multimedia component that required the least amount of storage
is
a. graphics
c. sound
b. video
d. text
17. The background software that loads the current program
(ie,MSWORD) is called
a. system software
c. integrated software
b. application software
d. communication software
18. Which of the following software would be used to draw the
architecture of an automobile?
a. integrated
b. desktop publishing
c. communication
d. computer-aided design
Review Questions – Short Answers
1. What is the difference between application and system
software?
2. Discuss the role of device drivers.
3. Explain the difference between special-purpose programs and
general-purpose programs?
4. Explain what a spreadsheet is, what is used for and give an example
of a spreadsheet program.
5. Explain what is meant by an integrated software and give an
examples.
6. Define desktop publishing.
7. Explain what a spreadsheet is, what is used for and name examples
that can be used on a PC
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83
8. Explain what is meant by integrated software and give
examples?
9. What are the three areas of artificial intelligence?
10. Define desktop publishing?
Additional Readings
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition. McGraw Hill, New York, 2011.
June Jamrich Parsons & Dan Oja, New Perspectives Introductory
Computer Concepts 8th Edition, Thomson Course Technology
References
Timothy J. O‟Leary & Linda I. O‟Leary, Computing Essentials 2007:
Complete Edition, McGraw-Hill Irwin, ISBN 978-0-07-351667-7
June Jamrich Parsons & Dan Oja, New Perspectives Introductory
Computer Concepts 8th Edition, Thomson Course Technology, ISBN: 0619-26764-X
Peter Ware, Phillip Cooke, Dieter Opfer & June Wall, Information and
Software Technology 7-10, Jacaranda, ISBN: 0-7314-0168-9
Carole Wilson, Exploring Computing Studies, Second Edition,Ca,bridge
University Press, ISBN: 0-521-78714-9
Gary B. Shelly, Thomas J. Cashman, & Misty E. Vermaat, Discoverign
Computers 2003, Concepts for a Digital World, Thomson Course
Technology, ISBN:0-7895-6514-5.
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Chapter 3
The Internet and the Web
Internet: network of networks
WWW: multimedia interface
After completing this chapter, you will be able to:
1. Differentiate between internet and WWW
2. Discuss the advantages and disadvantages of internet
3. Identify and compare different search tools
4. Identify different web browsers
5. Describe different web technologies
The Internet and the Web
85
3.0 Introduction
There has always been a misconception between the terms internet and
the World Wide Web (WWW). Most people think it is the same thing.
This chapter will clearly show the major difference between the internet
and the WWW. Internet today can support various kinds of applications
and communications. Searching information over the internet has
become ever so easier with the search tools that are available. People all
over the globe are connected via the internet. Communication over the
internet now is as easy as talking to your friend sitting beside you. This
is explained further with use of web utilities and social networking. Web
utilites provide users a convinient way to interact with internet whether
for business or personal use.
From small sized to large business organizations and the people in
general, all benefit with the advancement of internet technology.
However, there has also been a negative side to this huge growth in
internet. A huge increase in internet related crime is becoming common.
This is known as cyber crime. Some cyber crimes are discussed under
the disadvantages of internet.
3.1 The Internet and WWW
Internet is simply a network of networks. It is the actual physical
network that spans the entire globe. It is made up of computers, handheld
devices, cables, switches, routers, satellites and wireless devices.
Everything that can be accessed on/from the internet is known as
resources. These resources are simply stored on some devices usually
known as servers. Servers are computer with huge storage and
processing capabilities.
The World Wide Web (WWW) simply provides means and ways to
access the internet‟s resources. It gives a multimedia interface whereby
we can easily interact with the resources that are available on the
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internet. Multimedia means a combination of various forms of media.
For example: animations such as growing/shrinking text, hypertext,
sound, images and videos. WWW organizes information by using
hypermedia. Interface means a way of interacting with these media,
usually by clicking on hyperlinks or simply on images to view of save it
on your computer.
Figure 3.1 Internet map
In order to access the WWW, you need a browser. A browser is a
program that allows you to launch the desired web site for example,
Internet Explorer, Mozilla Firefox, Opera, Apple Safari, Google Chrome
and Netscape. Every website has a uniform resource locator (URL) or
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simply known as a website address. To launch a particular website, you
need to type the URL in the address box of your browser.
URL example:
http://www.usp.ac.fj
For this URL, http stands for Hypertext Transfer Protocol, the protocol
used to accessing most web sites. www, the subdomain, is the network
consisting of millions of internet sites that offer hypermedia resources.
usp.ac.fj is the known as the domain name and .fj is known as the
country code and for some URLs it called the top level domain. .ac
means academic.
Discovery Learning:
Identify, name and explain the different parts of some URLs
including the directories and file names
Apart from the browser, you must also have access to the internet in
order to utilize the web services. Internet access is usually granted by
Internet Service Providers (ISP). Some common ISPs in Fiji are
Connect Fiji, Unwired Fiji, Vodafone, Kidanet by Fintel and USP
through AARNET for USP students/staff only.
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The Internet and the Web
Review Exercise 3.1
True/False
a)
b)
c)
d)
Internet and WWW are same.
Multimedia can be used as hypermedia.
.com is an example of a top level domain code.
Browsers are programs that allow access to Web resources.
Completion
a) The domain code .ac stands for _________.
b) A(n) ________________ is the protocol used by browsers to access
websites.
c) The ________ provide internet service to its subscribers.
Short Answer Questions
a)
b)
c)
d)
What is the difference between internet and WWW?
Explain the parts of an URL?
Give five examples of URLS?
What is hypermedia?
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3.2 Communication and Search Tools
Communication
There are several types of communication possible over the internet. The
most common form of communication is electronic mail (e-mail). E-mail
is the sending and receiving of electronic messages over the internet.
There are two main types of e-mail. Web-based e-mail enables you to
access your email account from any computer and usually store your emails on a Web server. Google‟s G-mail, MSN‟s Hotmail and Yahoo
Mail are typical examples of these. The other type is the client based email, which consists of an email program you install on your computer
where the e-mail downloaded and stored locally on your computer. In
order to send and receive and email, you need an email account and
internet access. The most commonly used client based e-mail programs
for email are: Microsoft Outlook, Mozilla Thunderbird and Apple Mail.
A typical email message has three basic elements: header, message and
signature. The header is typically made of three sections: Address,
Subject and Attachment. Address: This is the section where you type the
email address of the person you are sending the message to. Subject:
gives and brief topic/heading as to what the message is about.
Attachment: any other item that is not directly part of the message can be
tagged together with the message, for example images, small videos,
music and other files.
The message comes after the header, this is where you simple type the
message you want to send the other party. The final part is the signature
which is simple the additional information of the person sending the
message. This signature is set once only and is tagged automatically with
the message every time you compose a new email message.
The second major form of communication these days is through instant
messaging (IM) and chat. Both IM and chat offer live and direct
communication however, IM is more sophisticated compared to chat.
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Header
Signature
Message
Figure 3.2a MS Outlook email composition
In addition to text messages, IM also allows file transfer, voice and video
communication. Some common examples of IM are Skype, MSN live
messenger and Yahoo messenger. You must note that at present there is
no cross communication possible between different IMs. For example
and yahoo messenger user cannot communicate with a Skype user.
Chat on the other hand offers only text based messaging. However, this
is far more favored and utilized simply because it costs less. Sending
plain text messages over the internet is much cheaper than
communicating via live video.
Discovery Learning:
What are the other forms of communication apart from e-mail,
IM and chat? Describe them.
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Search Tools
Search tools (also known as search engines) are programs that enable
searching for relevant information on the WWW much easier. Most
search engines present a default choice of everything category-websites
for the information being searched for.
However, the user can select a search category
for images, videos, scholar articles, news,
maps, shopping and many more for a more
refined and direct search. The world‟s most
widely used search engine today is Google.
Search engines
 Google
 Yahoo
 MSN
 Bing
 WebCrawler
Figure 3.2b Google search engine home page
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The Internet and the Web
Review Exercise 3.2
True/False
a) The three parts of an e-mail header are address, subject and
attachment.
b) Google chrome is a search engine.
c) IM is more popular than chat.
Completion
a) Skype is an example of ________________.
b) ____________ allows people to communicate direct and live by
sending plain text based messages.
c) The header of an email comprises of ___________, __________ and
___________.
Short Answer Questions
a) Compare and contrast IM and chat.
b) What is purpose of the signature in an email?
c) Describe the steps to set up a signature for your e-mail account.
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3.3 Web Technologies
Web Utilities
Web Utilities are specialized programs that make using the internet and
Web easier and safer while search tools make searching for appropriate
information on the Web much easier.
A major web utility is known as the plug-in.
A plug-in is a program that can be loaded
automatically together and as part of the
browser thus enhancing the browsers
capabilities in displaying information
especially images and videos.
Plug-ins
 Acrobat Reader
 Media Player
 Quick Time
 Real player
 Shockwave
Another web utility is called a
filter. Filters simply allow
blocking access to certain websites.
Filter programs are usually useful
for parents to use to block access to
the unwanted sites that their
children may be exposed to.
Figure 3.3a Plug-ins
File transfer utilities such as file transfer protocol (FTP) enable the user
to upload and download files. Uploading is the process of saving files
from your local computer to the internet for example, saving your photo
on the Facebook website. Downloading is the process of saving files
such as music, video, images or any other information from the internet
to your local computer. Most websites these days enable users to upload
and download files, for example USP‟s Moodle website allows USP
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students to download lecture notes and tutorial questions/solutions as
well as upload their assignments for marking.
A more convenient way of transferring files is through a peer-to-peer
networking (explained in chapter 7). These programs allow you to
bypass any website to transfer files (can be very huge files like movies)
directly to another person‟s computer. Limewire, Frostwire and Bit
Torent are such programs.
Social Networks
The fastest growing use of the internet today is social networking. This
simply allows people all over the world to be connected to each other
through the internet. Social networking also offers people gaming and
file sharing possibilities. The most common application used is chat.
Through chat people communicate direct and live with their friends,
family and colleagues. Social networking can be categorized as follows:
reuniting sites, friend of a friend sites and common interest sites.
Examples of free social networking sites are given in Figure 3.3b.
Discovery Learning:
Describe the three categories of social networking sites and
give at least two examples of each category.
Blogs
A blog is a journal or newsletter that is updated frequently and intended
for the general public. Blogs reflect their author‟s philosophical
reflections, thoughts, ideas and opinions on social, political and
information and communications technology (ICT) related issues.
Sometimes it is also used as a way for families or groups of friends to
keep in touch. Automated tools allow users (even with little technical
background) to easily create and maintain blogs. Blog sites like
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www.blogger.com and www.blogcatalog.com, offer such tools and free
space for blogs which also includes uploading photos.
Figure 3.3b Free social networking sites
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The Internet and the Web
Discovery Learning:
Find some examples of blogging websites. Observe and write
the common features amongst them.
Wikis
A wiki is a type of website that allows users to add, modify and delete
contents. Wikipedia, the online encyclopedia is the best know example
of this. The only problem with wikis is the quality and accuracy of the
content added by users. Some open source software such as Media Wiki
and TWiki are available for creating wikis.
Discovery Learning:
Select any topic of interest to you. Go to the Wikipedia website
and search for that topic. See if you understand the explanations
given and if not, try and add your own comments. Be sure not to
delete any other comments.
RSS Feeds
RSS (Really Simple Syndication) feeds provide a more convenient and
fast way to distribute information. RSS pulls the latest updates from
news, sports, entertainment, blogs, wikis and social network websites
that you have subscribed to and brings these updates at one convenient
place. Most people usually activate RSS feeds into their e-mails. Using
Outlook to subscribe to an RSS Feed is quick and easy and does not
involve a registration process or fee. After you subscribe to an RSS Feed,
headlines will appear in your RSS folders. RSS items appear similar to
mail messages. When you see a headline that interests you, just click or
open the item.
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Podcasting
A podcast is an electronic audio file, such as an MP3/4 file uploaded on
the Web for users to download to their mobile devices like iPods,
iPhones, and iPads. It is like a personal radio station on the internet.
iTunes and IPodder websites collect and store podcast for everyone to
download. One example in Fiji is the Vodafone‟s hello tunes.
Discovery Learning:
Describe the difference between an iPod, iPhone and iPad.
Review Exercise 3.3
True/False
a) A plug in is program that is independently activated to enhance the
capabilities of a browser.
b) Filters are programs for blocking access to certain sites.
c) Uploading is the copying of files from the internet.
d) Blogs allow news updates to be fed into your email.
Completion
a) The three types of web utilities are _________, ____________ and
___________.
b) _____________ enables people to download music to their phones.
c) The most commonly used application in social networking is _____.
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Short Answer Questions
a) What is the difference between a reuniting and common interest
social network website? Give two examples of each.
b) Describe how RSS feeds work.
c) Give an example of podcasting.
3.4 Summary
1. Internet is the actual actual physical network that spans the entire
globe. It is made up of computers, handheld devices, cables,
switches, routers, satellites and wireless devices. WWW is the
multimedia interface to the resources available on the internet.
2. The most widely used communication tool over the internet is email.
An email is made up of three parts, header, message and signature.
The header has further three elements, address, subject and
attachment.
3. Search engines allow people to search for their desired information
on the WWW easily. Different categories allow search to be more
refined and subject focused.
4. Web utilities allow safe and convenient ways to surf the net.
5. Social networks connect people, friends and colleagues all over the
world.
6. Blogging allow people to express their opinions on certain social,
political, and ICT related issues.
7. Wikis allow people to add, delete and modify contents posted on a
website.
8. Podcasting enables people to download music to their mobile
devices.
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Key Terms
e-mail
search engine
plug-in
chat
ergonomics
filters
wikis
RSS
blogs
instant messaging
podcasting
Review Questions – Multiple Choice
1) Rules for exchanging data between computers is
a. Prototype.
b. Procedures.
c. Protocols.
d. Programs.
2) The fastest growing activity on the internet is
a. Blogging.
b. E-mailing.
c. E-commerce.
d. Social networking.
3) The extensions, .com, .edu, .mil, .net and .gov all refer to
a. Protocols.
b. Domain codes.
c. Domain names.
d. Subdomain names.
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4) Highlighted text on a web that connects other web sites or places
within the same website is called a
a. hyperlink.
b. plug-in.
c. filter.
d. blog.
Review Questions – Short Answers
1)
2)
3)
4)
5)
Discuss the advantages and disadvantages of internet.
Briefly describe the difference between the internet and the WWW.
What is social networking? Give three examples.
What is the difference between blogs and wikis?
Explain how plug-ins works? Give four examples.
Additional Readings
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition. McGraw Hill, New York, 2011.
Bidgoli, H. MIS2. Course Technology, Cengage Learning, Boston USA,
2010.
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Chapter 4
Computers and Information Processing
“So, what you can do in Microsoft Word is what
Bill Gates has decided. What you can do in
Oracle Database is what Larry Ellison and his
crew have decided.” ~ Ted Nelson
After completing this chapter, you will be able to:
Read
more:
1. Distinguish between data and information
http://www.brainyquote.com/quotes/key
2. Recognizewords/database.html#ixzz1eikIRNCye
the role of information in decision making.a
flatthe
file.
3. Learn about
importance of databases in data management
4. Explain the fundamental concepts in a database management
system (DBMS).
--Introduction to databases, fredshack.com
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Computers and Information Processing
4.0 Introduction
While computer affect our lives in many ways, what they do basically is
solve problems. They are therefore problem-solving tools providing
computer solutions to many repetitive tasks that normally would require
a lot of time and manual labour.
There are seemingly endless amounts of information in our society. Each
day, as scholars and professionals ponder new ideas and ask questions, or
as events unfold, more new information is created. These information are
an be described as processed or meaningful data, data context or any
collection of words, numbers and symbols, organized so that it is
meaningful to the person using it.
Have you performed the any of the following tasks in the past few weeks?
Figure 4.0 Commonly used Web Applications
You definitely must have used the internet to do one of the following
tasks:
i.
Checked your web email (Gmail, Ymail or Hotmail)?
Computers and Information Processing
103
ii.
Searched the Library for a book, etc
iii.
Used the MOE exams website for information or your results.
iv.
Searched for products on a website
v.
Updated your profile details on Facebook or any other social
networking site.
How do you think it is possible to meet the data requirements for
each of the listed task?
All these efficient means of data access and data management has been
made possible by a database. Databases are designed to offer an
organized mechanism for storing, managing and retrieving information.
Discovery Learning:
What are the 2 methods a user interacts with a Database?
Some databases store confidential and important information and hence
require passwords and other security features in order to access the
information. Databases can operate on a standalone machine or can be
accessible in a network environment such as the Fiji Governments
intranet and the internet.
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Computers and Information Processing
4.1 Data and Information
Data is raw measurements and observations in the form of text, numbers,
symbols, images, and sounds which on their own have no meaning. Data
may be made up of numbers called numeric data, text called alpha data
or a combination of both numeric and alpha data called alpha-numeric
data. Examples of data include






Height of a student, suppose 1.5m, is data;
His name, suppose Josaia, is a data;
His weight, suppose 67kg is a data;
His hair color, suppose brown is a data; and so on.
Number of hours worked, suppose 40hrs.
Number of units of electricity consumed, suppose 75kw.
Information is data organized and presented with context and meaning
which can be evaluated, that is, statements can be made about it, either
true or false and coherent or incoherent. Examples of Information
include:
 The average height or weight of Form 5 students, suppose
1.58m, is information;
 The average weight of the class, suppose 61kg, is information.
Another Example of Data vs Information:
Suppose Avinesh got 58 in Math, 76 in English, 69 in Physics and 82 in
Computing Science in his Short test 1.
Total Mark = 58 + 76 + 69 + 82 = 285 (information).
Here, the individual marks are data but the total mark that calculated is
information. Processing helps transform data into information.
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Figure 4.1a The Input/Output Process
Data Organization
To be processed by the computer data is typically classified into groups
or categories as shown in Figure 4.1b. Each group is more complex than
the one before.
Character
Field
Record
File
Database
Figure 4.1b Database construction
Character is a single letter, number or special character such as
punctuation marks, the $ sign etc. These are the smallest units of data
representation.
A Field (column) contains a set of logically related characters. For
example on a form, a person‟s first name is a field, the last name is
another field, street name is another field etc.
Record (row) is a collection of logically related fields represented
together. All the contents of a form concerning one particular itinerary
can be called a record. If a field is used to represent different parts of a
subject a record would be a collection of field concerning each part of
that subject.
File (table) is a collection of logically related records. All forms (which
are records) are kept in one location that is a file.
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Computers and Information Processing
Database integrates data. It is defined as the collection of integrated data.
By integrated we mean the data consists of logically related files (linked
tables).
Characteristics of data and information
1) Data are the raw materials
1) Information is the resultant
(input) of information
(output) version of some data.
2) Data is a distinct piece of
2) Information always be
information
processed or organized
3) Data is disorganized or
3) Information provides context
unprocessed.
which gives meaning to data.
Table 4.1a Difference between data and information
Review Exercise 4.1
Short Answer Questions
1. If you are applying for an interview, give some examples of data and
information you will furnish to your potential employer.
(Differentiate between what data and information you will provide)
2. Suppose you are using Facebook. Give some examples of data and
information displayed on the social networking site.
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107
4.2 Role of information processing in decision making
Data processing produces information which is required to form
conclusions and make decisions on plans of action. Good decisions are
based on sufficient and timely information. Insufficient information
usually does not help in making good decisions. Because the computer
can be handle large amounts of data efficiently and present summaries of
information effecting e.g. in the production of tables and graphs, it is
considered to be essential for decision makers.
Data processing is the process of manipulating data in one or more of the
following six procedures:
Collecting Data
Data may be collected from a number of sources. The most common
form of data collection is data entry from source documents. For
example, collecting test marks for Form six students. These marks are
written on a sheet of paper and then can be entered into a database or
spreadsheet for manipulation
Organizing Data
Data must be arranged into relevant categories so that the relationships
between various facts can be seen as shown in Table 4.2a.
Name
Anshu
Retasha
Ravneel
Computer Mark
78
66
88
Table 4.2a Sample Student Dataset
Combining Data
This involves the combination of similar data to reduce the number of
data items to be processed. For example:
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Computers and Information Processing
Name
Anshu
Retasha
Ravneel
Computer
Sc.
78
66
88
Mathematics
67
77
89
Total
Marks
145
143
177
Table 4.2b Combined Student Data
Sorting Data
This involves the arrangement of data in the order that is needed e.g.
alphabetical, ascending/descending, chronological (SEQUENCIAL) etc.
Name
Anshu
Ravneel
Retasha
Alphabetic order
Computer Sc.
78
88
66
Table 4.2c Sorted Student Data
Manipulating Data
This involves performing calculations on the data e.g. finding the
average of a set of numbers, calculating the percentage of a quantity etc.
Summarizing
Data is summarized based on the contents of the relevant categories as
shown in the tables below.
Name
Anshu
Retasha
Ravneel
Computer Sc.
78
66
88
Table 4.2d Student Data
Name
Computer Sc.
Position
Anshu
78
2
Ravneel
88
1
Retasha
66
3
Table 4.2e Summarised Student Data
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109
Traditionally data is processed in 2 ways:
Batch Processing
Data is collected over several hours, days or even weeks (period of time).
It is then processed all at once as a batch. Example a bank credit card
account which is updated monthly or a weekly or a passbook savings
account which is updated at the end of the day.
Real Time Processing
Occurs when data is processed at the same time the transaction occurs.
For example, ATMs and online bill payment systems. Real time
processing is made possible by the availability direct access storage.
Review Exercise 4.2
Short Answer Questions
a) List three applications of databases in
 Business.
 Government.
 Home.
b) Briefly explain the following application areas of databases
 Inventory
 Accounting
 Mailing List Management
 Libraries
 Banking
c) What is the difference between an operational and a transactional
database?
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Computers and Information Processing
4.3 Information Retrieval
This section will focus on databases which is the most widely used data
storage, manipulation and retrieval tool.
A database is a collection of related files that can be retrieved when
needed. It is usually stored in a secondary storage device e.g. hard disk
or magnetic tape. The data in a database are accessed using an
application program called a database management system (DBMS).
Students normally confuse the definition of the two terms ; database and
Database management systems. A DBMS acts like a custodian for all the
information in a database.
A database is a store of organization that can be recalled if and when
required. The information in the database can be organized or
manipulated to show specific patterns or to make selection of specific
pieces of information
A file is a collection of data stored in secondary devices. It is composed
of a number of related records each containing information about a
particular subject e.g. a file of students‟ grade will contain a record for
each student. A paper based file contains pages of printed information
about a subject. Electronic files Systems include storing data in MS
Word, MS Excel, Text and .DAT files.
A Record contains a number of fields which are related. A field is
usually an important feature of the subject whose data is stored in a
record e.g. in the file of students‟ grade, a record may contain the
following fields:



Students Name
ID No.
Form



Subject
Marks Gained
Grade
A key field is a field that can be used to locate one particular record. In
the above example, the students‟ ID No. can be used as a key field
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111
because it uniquely identifies the record. Sometimes one key field may
not be enough identify a record e.g. in airline reservations, a passenger‟s
name is not a useful key field because there can be more than one
passenger with the same name traveling on the same flight. In the same
way, a flight has so many passengers on it and the same flight number
goes up each day making the flight number alone and unsuitable key
field. But combination of a passenger‟s name, flight number and date of
the flight will be able to uniquely identify a record.
Advantages of a Database
The four advantages of having databases are
1. Sharing
2. Security
3. Fewer Files
4. Data Integrity
Discovery Learning:
How does a database increase end-user productivity?
Sharing in organisations, information from various departments can be
readily shared with other departments and users.
Security enables users proper and authorised access to only the kind of
information they need to know. For example the payroll department may
have access to employees pay rate but other departments may not.
Access is restricted to authorized users only.
Fewer files mean less storage requirements. With several departments
having access to one file, there are fewer files in the information
systems. Excess storage (extra copies of information) called data
redundancy is also reduced. Microcomputers are linked by networks to
file servers which give access to databases located on and shared to the
servers.
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Computers and Information Processing
Data Integrity enables data to be updated instantaneously. Older filing
systems did not have data integrity i.e. a change made in a file in one
department might not be made in another copy of the file holding the
same information in another department. This can cause serious
problems and conflicts when data is used for important decisions
affecting both departments. Data integrity is when changes made in one
file to a particular data, updates are made in other files which contain the
same data as well.
Disadvantages of Databases
The benefits and improvements database systems have brought about in
data management is unquestionable. Database systems have enabled
more sophisticated use of the data. However, apart from the many
advantages of a database system, there exist some significant
disadvantages such as the following.
Increased costs for maintaining database systems since it requires
sophisticated hardware and software. The cost of hardware maintenance,
software licensing, upgrades and skilled DB professional needed incur
quite a significant cost.
Management complexity is the systems interfacing cost in terms of
company's resources and culture as well as the security issues prevalent
must be assessed constantly.
Maintaining currency is keeping the system current, up-to-date and
personnel training costs tend to be significant.
Vendor dependence with the heavy investment related to DB systems,
companies might be reluctant to change vendors. This leads to limited
choice of database system components.
Frequent upgrade/replacement cycles occur when vendors frequently
upgrade their products which companies have to keep par with. Some of
these upgrades require hardware upgrades as well as personnel training
(users and administrators) incurring additional cost.
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Review Exercise 4.3
Short Answer Questions
1. Identify three situations in your community or school where people
are still keeping data in traditional files systems.
a. List two reasons why you feel a database is better suited for
storing information than a traditional file system.
b. List two reasons why the organization would still prefer to use
traditional files rather than a database to store information.
2. A database houses information in tables which are related, thus the
name Relational Databases. Discuss the following types of
relationships in a relational database and give examples.
a. 1 : 1 (one-to-one) Relationship
b. 1 : M (one-to-many) Relationship
c. M:M (many-to-many) Relationship
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4.4 Database Management System (DBMS)
A Database Management System (DBMS) is a program that manages the
following five functions.
Create records A DBMS provides a structure for the data and identifies
the relationships among the data.
Update records - A DBMS allows for the updating of files in the entry of
new data and it sees that new data conform to the defined structures
already existing.
Maintain records - A DBMS corrects errors of misspelling, omission in
content eg. File name or data. It allows for changes in the structure of the
database in cases where important information may have been left out or
useless information included.
Provide Access to records - Data may be accessed through the use of
command languages where the user types in the commands or prompting
systems where the user selects commands from menus. Depending on the
user‟s needs, information can be retrieved on various forms. Notes well
the difference between the use of commands and the use of menu-driven
or table-driven systems, their advantages and disadvantages.
Control the integrity and security of data - Most systems perform the
following to control the integrity and security of files
a. Maintain conformity to the database definition eg. By comparing
new entries to the database definitions to see that no errors are made.
b. Control updating particularly when many users use the database
simultaneously. Problems may arise when two users are trying to
update the same data at the same time.
c. Assure the existence of data in the case of technical problems which
may cause the loss of data. This may require complicated techniques
in restoring the data.
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d. Control access to the data to ensure that users can only see data
which they have legal access to.
e. Resource locking refers to maintaining a database so that its data are
accurately accessed and problems which can rise from having two or
more users working interactively with the data can be prevented. For
example, the double booking of a plane seat etc.
Common Errors in a Database
Content Error refers to wrong input or misspelling.
Structural Error refers to error or flaws in the programming or
definitions of the database.
Discovery Learning:
Gives specific examples of errors that exist in a school database and
justify whether they are Content or Structural errors?
Some common DBMS are MS Access, Oracle, MS SQL Server, MySQL
and DB2. The key components of DBMS software consists of the
following.
Data Dictionary
A data dictionary contains a description of the structure of data (fields)
used in the database. For each particular item of data (field), it defines
the properties of that item for example the name of that field, the data
type, the length caption etc. It also specifies the character length of a
field and whether the field is a key field.
Query Language
The access to most databases is accomplished through the use of query
languages. A query is simply a question that you can ask the database to
provide relevant and specific information only on demand. This is an
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easy way to use a language understandable to most users and uses simple
natural language structures like English words.
One of the most widely used query language is called the Structured
Query Language (SQL). SQL uses commands such as ADD,
COMPARE, and DISPLAY, SELECT, JOIN, UPDATE, etc to select
relevant and specific information only.
Report Generation
This part of the DBMS software enables a user to design and format
reports for presentation and decision making. Reports are normally
generated on form the results of the queries but organized in a very neat
and presentable way so that it is easily understood by everyone reading
the report.
Review Exercise 4.4
Short Answer Questions
a) What is the purpose of a DBMS and how is it different from a
database?
b) What are the drawbacks of using file systems to store data?
c) Find out the difference between
i.
Data Definition Language (DDL)
ii.
Data Manipulation Language (DML)
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4.5 Database Security
Since databases are a valuable asset for all organizations, security is a
vital issue. One concern is that personal information about people stored
in databases will be used for the wrong purpose. For example a person‟s
credit history, medical records maybe used for hiring and making
promotional decision.
Another concern is with preventing unauthorized users from gaining
access to databases either directly or through a network. Another serious
concern is the prevention of the intrusion of a virus. They may be
introduced by end-users unknowingly or intentionally by unauthorized
users. There have been numerous cases where computer viruses have
been launched into databases doing un-repairable damages.
Computer viruses are hidden instructions that migrate through networks
and operating systems and become embedded in different programs and
databases and do harm. See chapter 5 for more details regarding viruses.
Discovery Learning:
Give 2 reasons for controlling access to a database?
Security can require putting guards in a company‟s computer room and
checking everybody‟s ID. Some security systems automatically check for
fingerprints. Security concerns are particularly important to
organizations using wide area networks. Violation of computer systems
can occur both physically and without entering secured areas. See
chapter 5 for more details regarding types of computer crimes.
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4.6 Summary
1. Databases are designed to offer an organized mechanism for storing,
managing and retrieving information.
2. Data is raw measurements and observations in the form of text,
numbers, symbols, images, and sounds which on their own have no
meaning.
3. Information is data organised and presented with context and
meaning which can be evaluated
4. Data processing produces information which is required to form
conclusions and make decisions on plans of action.
5. A database is a collection of related files that can be retrieved when
needed.
6. Resource locking refers to maintaining a database so that its data are
accurately accessed and avoid problems which can arise from having
two or more users working simultaneously with the data.
7. Structured Query language (SQL) is used to select information
or records from a relational database.
8. Database security concerns the use of a broad range of information
security controls to protect databases against compromises of their
confidentiality, integrity and availability
Key Terms
data
DBMS
record
data integrity
real-time processing
field
database
SQL
resource locking
batch processing
information
data dictionary
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Review Questions – Multiple Choice
1. Numbers, pictures or words without context are known as?
a. Data
b. Information
c. Knowledge
d. Communication
2. Which of the following is correct?
a. information leads to data, and data leads to knowledge
b. data leads to information, and information leads to knowledge.
c. knowledge leads to information, and information leads to data
d. data leads to knowledge and knowledge leads to information
3. In a database of newspaper, journal or magazine articles, each record
represents:
a. one magazine, journal or newspaper
b. one author
c. one article from a magazine, journal or newspaper
d. all of the above
4. You are making your own database so you can organize information
about your „Top 100' movies. You want to include information like
Title, Actor(s), Director, Year, Genre, etc. Each record in your
database will represent:
a. an actor
b. a director
c. a year
d. a movie
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5. A database program replaces what piece of office equipment
a. typewriter
b. photocopier
c. FAX machine
d. filing cabinet
6. Database Management System(DBMS) is/are
a.
b.
c.
d.
Computer Programming Language
Collection of interrelated data
Query Language to access a database.
DBMS provides an environment that is both convenient and
efficient to use.
7. John is working in the customer table and needs to know what
customers are located in Florida. To find the information he would
____.
a. create a new table
b. create a new query
c. create a new form
d. utilize the Database Wizard
Review Questions – Short Answers
1. Differentiate between batch processing and real-time processing.
Give examples to support your answer.
2. What are the different types of file organization?
3. List six (6) procedures that are usually involved in information
processing?
4. What is a key-field used for in a data table?
5. Outline the role of a Database Administrator.
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6. Database and data management are at a turning point. Among the
drivers are changes in architecture like cloud computing and the
needs to deal with large amounts of data. What is cloud computing
and how has it changed data storage and data management?
Additional Readings
Donald D. Spencer. Introduction to Information Processing (3rd ed.).
Prentice Hall PTR, Upper Saddle River, NJ, USA.
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition. McGraw Hill, New York, 2011.
Raghu R. and Johannes G., Database Management Systems, (3rd ed.),
McGraw
Hill,
2000,
ISBN
0-07-246563-8.
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Chapter 5
Computers in Society
"There are several reasons why computers have become so
important. They operate at extremely high speeds, have the ability
to store and retrieve vast quantities of information, and can make
decisions based on the results of previous operations. With just
these primitive functions, a generation of programmers has
created a body of software that can control a missile, intercept a
message, and predict the results of an election, or automates a
factory."
David Brandon and Michael Harrison, the Technology War
After completing this chapter, you will be able to:
1. Discuss the relationship between the computer and the society.
2. Identify the current trends in the development of computer
systems and the use of computer application to various
organizations and government offices.
3. Describe the major privacy laws, the security threats posed by
computer criminals, computer crime and other hazards.
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5.0 Introduction
The dawn of the new computer era glows before us with the new
innovative ideas, ways of thinking and living. The amount of information
and technology is said to be changing every 6 months from Mobile
phones, I-pad, and computers (notebooks to desktop PC). The only way
to keep up with these is to understand, how technology works and the
ability to control them so that human interaction would be able to accept
and live with the changes.
5. 1 Computers in Society
The computerization of society refers broadly to the widespread use of
computers, which has led to the restructuring of many functions in
society. The computerization of society is the result of economic and
technological trends. In economic trend the computer can store, process
and communicate information. It has helped to enhance the value of
information and add value to products and services. For example, the
clients‟ data in an insurance company can process and create profiles
which enable the company to match its services better with its clients.
Technological trend on the other hand is the development of
microelectronic technology which has led to changes in both the nature
of the products produced and the process by which the products are
designed and manufactured.
In an office, the computer can automate the tasks of typing, editing,
copying, filing, preparing reports, sending messages, preparing budgets
and accounting work.
Discovery Learning:
What are some important factors to consider when designing
an automated office?
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Impacts of Computerization
Positive Impacts
Negative Impacts
New jobs and job efficiency
Reduction in social interaction at
work
New products and services
Pressure
Increase in quality of products
Exposure to unwanted activities
Overall increase in the quality of Security
living
Table 5.1 Positive and negative impacts of computerization
Enhancing efficiency across multiple sections of the society
The management productivity can be improved by the use of computers
because managers/decision makers can receive timely, sufficient and
meaningful information which enable them to make informed decisions
at the right time. An information society is one in which most of the
population is involved in gathering, processing and communicating
information rather than physically producing goods. Some information
workers are clerks, lawyers, doctors, architects, educators and newsmen.
The computer, with its capability to store, organize, retrieve and
communicate large amounts of information in many different ways allow
organizations to consider information as a strategic resource that adds
value to the goods or services their company offers.
Transportation – Most road users nowadays have used computers to
monitor the use of fluid levels, temperatures and electrical systems.
Computers are also employed to determine road network connectivity
from point A to point B using Global Positioning System (GPS),
especially for locating supermarkets, building locations and tracks
vehicles for long distance travelling, for example, the Fiji Water delivery
trucks.
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125
An important part is the air control
traffic systems, where computers are
used to control the flow of traffic
between airplanes which need precise
and accurate information of landing
and takeoff.
Figure 5.1a GPS device
Paper Work – The extensive use of computer systems in most public and
private companies or even schools, and universities, eventually reduce
the amount of paper work. In the past most business organization
preferred paper work, however, not realizing that it was making the
administration work more tedious and error prone. Computer makes their
work easier, faster and more effective than the manual system.
Banking – Computers speed up record keeping and allow banks to offer
the same day services and even do it yourself over the phone banking for
example ANZ, BSP, Westpac and also internet banking systems as
shown in Figure 5.1b. In addition to these computers are involved in
most transactions (money) as there is a better chance of detecting illegal
money laundering via internet on the use of credit/debit cards.
Education - It has been proven that with the use of computers, learning
becomes more successful which is why numerous forms of teaching
methods have been introduced involving the use of computers. It
enhances the student‟s knowledge at a faster pace compared to the
traditional methods of teaching and learning. Figure 5.1c shows USP‟s elearning management system – Moodle.
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Computers in Society
Figure 5.1b ANZ Internet banking home page for Fiji customers
Figure 5.1c USP‟s e-learn management system
Government - A government provides society with directions by making
and administering policies. To provide citizens with up-to-date
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127
information, most government officers have websites. For example, to
access the government website in Fiji, you will be able to get information
from: http://www.fiji.gov.fj. In addition to providing information via
computers, employees of government agencies use computers as part of
their daily work routine. In Fiji, ITC services enable officers to access all
government ministries‟ emails and websites as well. Computer systems
are used extensively by the disciplinary forces, for example, the Army,
Police and Navy. Furthermore, computers will need to be programmed
more appropriately so that they are precise and accurate in order to
provide the right information to support their investigations and evidence
they provide.
Figure 5.1d ITC website e-Government portal
Law Enforcement - Law enforcement includes computer modeling of
DNA, which has the ability to match traces of any form of criminal
activities such as murder - (blood samples). For example, movie series
such as CSI, MIAMI and NYPD have demonstrated the capabilities of
computers in determining the desired outcome of most crimes
committed.
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Computers in Society
Medicine & Health Care - Nearly every area of the medical field uses
computers. In most hospitals, doctors use computers to assist them in
diagnosing diseases of any kind. This type of computer is called the
Expert System, which is often used in most specific field of medicine,
for example, in conducting heart surgery, eye check and in detecting
various forms of diseases. Furthermore, computers are being used widely
in hospitals to assist medical staff in managing patients‟ records, doctors,
nurses, prescription [medicine] records as well as making, and
scheduling appointments of patients.
Review Exercise 5.1
True or False
a) Management productivity can be improved without the use of
computer.
b) The development of microelectronic technology led to changes in the
nature of the products
Fill in the Blank
a) The computerization of society is the result of _____________
and________________.
b) Computers which are used in hospitals to diagnose diseases of any
kind are called ____________________.
c) ____________________ is one in which most of the population is
involved in gathering, processing and communicating information
rather than physically producing goods.
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Short Answer
a) Briefly define the computerization of society?
b) Identify two related trends which have led to the computerization of
society.
c) Identify some local examples of how the computer is used to
increase efficiency and productivity in an organization.
d) Provide some examples of the positive social and negative social
impacts of the widespread use of computers.
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5. 2 The Latest Trends in Computer
The Internet, also called the Net, is a worldwide collection of networks
that links millions of businesses, government agencies, educational
institutions and individuals. One of the major reasons businesses, homes
and other users purchase computers is for Internet access. The use of
internet has enabled society to access global information and instant
communications. Internet access can occur from a computer anywhere; at
home, at work, at school, in a restaurant, from an airplane, and even at
the beach. Two widely accessed Internet services are the World Wide
Web and E-mails. Look back at chapter 3 for all web related activities.
A web database also known as an on-line database is a database which
usually resides on a database server. A database server is a computer
that stores and provides access to a database. Users can access
information on an on-line database such as television programs, movies
and videos, shopping for products or services, searching for a job,
making airline reservations etc. Apart from accessing information on an
on-line database, a user may also provide other types of information.
Many web sites request users to enter personal information such as
name, address, other personal details and preferences into an e-form. The
database then stores this personal information for future use.
Discovery Learning:
Give examples of online databases.
A teleconference also known as a video conference is a meeting
between two or more geographically isolated people who use a network
or the internet to transmit audio and video data. To participate in a video
conference, you need video conference software, along with a
microphone, speakers, and a video camera attached to your computer. As
you speak, members of the meeting hear your voice on the speakers. An
image in front of the video camera such as a person‟s face is displayed
on the monitor/screen of each participant. Using similar technology,
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131
home users today can make a video telephone call where both parties see
each other as they talk.
Figure 5.2a Video conferencing
Telecommuting is a work arrangement in which employees work away
from company‟s standard work place and often communicate with the
office using some type of communications technology. Some
professionals such as architects, writers and computer programmers
could work at home using a personal computer by logging into the office
network from home, and use emails to keep in touch with their office.
Workers telecommute for many reasons; for example:
a. Reduces time and expenses spent on travelling to the office.
b. Eliminates travel during unsafe weather conditions.
c. Allows a flexible work schedule so that employees can combine
work and personal responsibilities such as child care.
d. Provides a convenient, comfortable work environment for disabled
employees or those recovering from illness or injury.
Computer-Aided Design (CAD) software is a sophisticated type of
application software that assists a professional user in creating
engineering, architectural, and scientific designs. For example, engineers
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Computers in Society
can create design plans for airplanes and security systems. Architects can
design building structures and floor plans. Scientists can design drawings
of molecular structures. CAD software eliminates the difficult manual
drafting that design processes may require. With CAD, designers can
instantly make changes to a drawing or design and immediately view the
results. Three-dimensional (3-D) CAD programs allow designers to
rotate designs of 3-D objects to view them from any angle. Designs that
are created on CAD software are then fed into a Computer-Aided
Manufacturing (CAM) system, which permits computers to control and
direct the manufacture and assembly of a product. CAM software also
controls automated factory equipments, including machine tools and
robots.
Figure 5.2b Computer Aided Design in AutoCAD
Industrial Robots - are used in factories to perform assembly-line tasks
and also capable of performing a variety of tasks. This includes machines
which are used in automobile plants to do welding, polishing, and
painting. Some types of robots have claws for picking up objects and
handling dangerous materials.
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Figure 5.2c Car assembly line robot
Mobile Robots are those which act as transports and are widely used for a
variety of tasks. For example, the police and the military use them to
locate and disarm explosive devices.
Humanoids are designed to look exactly like humans. It is programmed
to mimic actual human behavior like talking, walking and making
gestures. Humanoids are becoming popular as ushers, waitresses and
shop attendants.
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Figure 5.2d Humanoid robots
Virtual Reality (VR) is the use of computers to simulate a real or
imagined environment which appears as a 3-D space. Virtual reality
allows you to explore and manipulate controls to experience the 3-D
space fully. Virtual reality is
used in practical applications
like training, engineering, ecommerce, science, and
medicine. Many companies
use VR simulations to train
people
who
operate
expensive and complicated
equipment such as airplanes
and ships before they try the
real stuff.
Figure 5.2e Virtual reality air to air
refueling simulator
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135
In Special Education - [the education of the disabled], computers can
individualize instruction to suit the particular educational needs of a
child with disability. They can be programmed to present lessons or
drills at a level of difficulty and speed appropriate for each child. They
can provide immediate and informative feedback, which is particularly
helpful for children with learning problems, for example, resolving
reading problems using reading software. With the help of computers
special education children can become active learners. As they learn to
control and interact with the computer, their work habits and study skills
improve.
Entertainment and educational software for personal computers includes
interactive games, videos and other programs designed to support a
hobby or provide amusement and enjoyment. Entertainment web sites on
the Internet offer music, videos, sports, games, ongoing Web episodes,
chats & more. The Internet also provides current, in depth, firsthand
information and also allows students to communicate with their peers
and experts around the world. Information offered on educational
software & on the Internet tends to be more interesting than textbooks,
because it is offered in a variety of forms such as graphs, pictures, text,
audio & visual formats.
Robotic wheelchairs have now been
developed for those who have severe spinal
injuries. A robotic wheelchair is outfitted
with sensors that recognize environmental
conditions, detect hazards and read
information from nearby buildings via IC
tags. That means the chair is able to
maneuver itself safely to a pre-specified
destination. It can also be operated
manually, and has wheel drive control and
emergency shutdown.
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Figure 5.2f Robotic
wheelchair
Computers in Society
Review Exercise 5.2
True/False
a) Artificial Intelligence is the application of Machine language to
computers.
b) A robot without a camera can guide machine tools, inspect products,
and identify homes
c) Microsoft Outlook and Outlook Express are two popular email
programs.
Fill in the blank
a)
The three different types of robots are___________,
b) ____________________ and _________________
c)
_______________ Software is a sophisticated type of application
software that assists a ___________user in creating
______________________________designs.
Short Answer
a) Identify some of the latest trends in computer usage.
b) Distinguish between a robot and an automated machine.
c) Explain the most controversial issue in the use of robots in
manufacturing.
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5. 3 Privacy of Information
Information has become an invaluable asset for both individuals and
organizations. As you become comfortable working with technology,
you will naturally explore methods of gathering, storing and exchanging
data. With this power in the form of knowledge, there is also the
potential tendency for abuse. When used with malice or neglect,
computer technology can become a tool for committing crimes or
infringing upon your individual rights or privacy. You probably think
first of the law. Of course that is right, but technology is moving so fast
that it is difficult for our legal system to keep up with it. The essential
element which guides how computers are used today is ethics. Ethics are
standards of moral conduct. Computer Ethics are guidelines for the
morally acceptable use of computers in our society or the standard
behavior regarding the use of computers for individuals and
organizations. There are four primary computer ethical issues:




Privacy concerns the collection and use of data about individuals.
Accuracy relates to the responsibility of those who collect data to
ensure that the data is correct and up to date.
Property relates to who owns data and rights to software.
Access relates to responsibility of those who have data to control
who is able to use that data.
Some ethical questions surrounding computers
Is it right for someone who buys a program to copy it for a friend?
Is it fair to tap into someone else‟s computer data files?
Should computer operators regard all data they process as completely
confidential?
Does a company owe a worker who has been replaced by a computer or
any consideration other than that prescribed by labour law or contract?
Table 5.3 Ethical questions
Information about individuals that may be kept in data files or databases
may include email & residential addresses, telephone numbers, financial,
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health, education and work experience, criminal record, credit history
and driving license record. Since that is the case, these data in a database
may then be misused through the inaccuracy of the data stored because
of inadequate updating, for example, a bank that does not update the
accounts of its depositors can ruin the financial status of its depositors.
Another way of misusing data in a database is through the indiscriminate
use of data for other purposes, for example, a credit card company
should not release credit histories of a prospective client to others
without the permission of the client. Information in a database can be
stolen by electronically tapping into the computer system and reading the
data, bribing employees to copy the data, or physically breaking into the
computer centre and stealing the storage devices. A database
administrator can protect a database against unauthorized access through
the screening and monitoring of the people handling the data, enabling
passwords, encryption devices, and special log-in routines and
appropriate physical protection.
Discovery Learning:
Give examples of ethical breaches in Fiji in terms of
computer usage.
Some of the major concerns regarding privacy are the spreading
information without personal consent. How would you feel if your name
and your taste in movies were made available nationwide? How would
you feel if someone obtained a driver‟s license and credit cards in your
name? What if that person then used your identity to buy clothes, cars
and a house? This is called identity theft. Identity theft is the illegal
assumption of someone‟s identity for the purpose of economic gain.
Spreading of inaccurate information occur due to mistakes in recording
which can quickly spread to other files. Cases of mistaken identity can
occur from these instances, where the electronic profile of one person is
switched with another.
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When visiting a Web site, your activity is monitored, that is, your
browser stores critical information onto the hard disk, usually without
your permission or knowledge. For example, your browser creates a
history file that includes the location of sites visited by your browser.
Another way your Web activity is monitored is by cookies or specialized
programs that are deposited on your hard disk from Web sites you have
visited. Spyware is used to describe a wide range of programs that are
designed to secretly record and report an individual‟s activities on the
Internet.
Discovery Learning:
Find examples of spyware.
Revision Exercise 5.3
Fill in the Blank
a)
The process of converting readable data into unreadable form is
known as ____________.
b) Characters to prevent unauthorized access are called ___________.
c) ____________monitors which sites you visit on the internet.
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Short Answer
a) Describe the sort of information about individuals whose profiles are
kept in databases.
b) Briefly explain how outsiders can steal information in a database.
c) Outline how a database owner can protect a database against
unauthorized access.
d) Explain the government‟s stand in protecting the misuse of
information in a database.
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5.4 Computer Based Crime
Computer crime it involves the use of computer and software for illegal
purpose. Computer crime takes many forms, from unintentional
disruption to vengeful acts to fraud. A computer crime is an illegal action
in which the person responsible uses special knowledge of computer
technology for illegal purposes.
There are five types of computer crimes.
The largest category of computer criminals consists of those with the
easiest access to computer namely the Employees. Sometimes the
employee is simply trying to steal something from the employer whether
it is the equipment, software, electronic funds, proprietary information,
or computer time. Sometimes the employee may be acting out
resentment and is trying to “get back” at the company. Not only
employees but also some suppliers or clients may have access to a
company‟s computer system known as the Outside Users. For example
bank customers who use an automatic teller machine. Like employees,
these authorized users may obtain confidential passwords or find other
ways of committing computer crimes.
In most organisations, people who committed cyber crime are classified
as Hackers and Crackers. For instance people think of these two groups
as being the same, but they are not. Hackers are people who gain
unauthorized access to a computer system for the fun and challenge of it.
Crackers do the same thing but for malicious purposes.
Organized crime has discovered that computers can be used just like
legitimate business people use them, but for illegal purposes. For
example, computers are useful for keeping track of stolen goods or
illegal gambling debts. In addition, counterfeiters and forgers use
microcomputers and printer to produce sophisticated-looking documents
such as checks and driver‟s licenses and currency.
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Computer fraud is other type of crime which is committed by exploiting
loopholes in a computer system, or by employing inside knowledge
about how a computer system works. Most computer fraud is committed
by insiders such as programmers who can attempt to escape detection by
covering up their tracks before the fraud is noticed.
Discovery Learning:
Give some reasons why people engage in computer based crimes.
Three Reasons for the increase in Computer Crime



Many more people now know how to operate the computer.
Many computers are now linked together through networks.
The easy access to large databases through microcomputers.
Four Reasons why it is difficult to detect Computer Crime




The crime is complex and is not easily discovered.
It is difficult to trace the guilty party once the crime is discovered,
because of the difficulty in finding evidence.
There are usually no witnesses although the crime can be taking
place in a room full of people.
Law enforcement people are usually ignorant and unaware of the
complexity of computer technology and as such are unable to guard
against misuse of the computer.
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Types of Computer Crimes
Data manipulation or data diddling - altering of data that is entered
and/exits in the computer. There are different types of data manipulation,
for example, altering school grades by putting false data into the
computer and altering or deleting information, „Salami slicing‟ which
involves skimming off minute amount of money from a number of bank
accounts & diverting it into the manipulator‟s own account. In banks
such crimes have been reported to have been committed where bank
clerks skim off money from „dead‟ accounts (accounts whose holders
have either migrated or died). This is hard to detect because each
individual slice is a fraction of a cent and while the slicing is going on,
all accounts appear to be in balance.
Trap Door is the creation of special password that enables one to get into
a program without being known.
Time Bomb is coding of a computer program so that it destroys itself
after running a certain number of times. This is often used by employees
who are not happy with the management of their organizations. It is also
used by software developers whose customers purchase on credit terms.
If they are not paid on time, the programs will destroy themselves, or the
developers will let their clients know how to „defuse the bomb‟.
Data Stealing is the stealing of data for a company‟s purposes and using
it for other purposes.
Time Stealing is the use of a computer without authorization, therefore
stealing the money paid in rent for the use of the computer.
Electronic Eavesdropping is the tapping of communications lines in
which data and information are sent. This task is often undertaken by law
enforcement units or spies from a foreign territory.
Industrial espionage - The stealing of designs, marketing plans or other
trade secrets of one company and selling the information to another.
Automated Larceny – use of computers to steal or defraud money from
any computerized accounting system.
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Software Piracy is the illegal or unauthorized copying of software.
Computer users must note that software is not bought or purchased,
rather it is licensed. Publishers retain the ownership therefore users have
no right to copy the software or its documentation. The license
agreement which is provided with the software usually states the terms &
conditions of the license. Normally, approval is given for the making of a
backup copy of the software to guard against damage of the original but
no multiple copies or backup are allowed.
Copyright and License agreement
Copyright Ownership is the legal right of the owner of software to
control the copying, distribution and use of the program.
Copy Protection is the use of special hardware and software techniques
to prevent the illegal copying of software. Software approach protection
is the use of special codes on the original disk. A program will not run
unless it can find this special code. For example, software is often
installed into the computers via a CD. These CDs have a “CD KEY”
(special numbers) that has to be entered during the installation process. If
this is not done, the software will not load into the computer system.
Site License is a contract which allows a user to make copies of a
software package for use at one site, for example, Computer Education
Centers and School Computer Labs have license agreements to make
several copies of Microsoft software for use in these centers or labs. A
Site license is a better alternative to Copyright and it is used in a lot of
organizations. This is because the site license is an agreement or mutual
agreement between the users and the developer but a copyright has no
binding agreements. It‟s left at the discretion of the developer.
Furthermore in site licensing there is no need to purchase copies of the
same program thus saving thousands of dollars.
Shareware refers to copies of programs which a publisher distributes
freely to users for inspection. If a user agrees with the program and
wishes to get a licensed copy of it, he or she pays the publisher. Getting
licensed copies will enable a user to get updated copies of the program
and its documentation. The shareware system is usually adopted for
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marketing small or less sophisticated programs because of the high risk
of copying involved. By copyright, a developer is protecting only the
„expression‟ of the program. Any rewriting of the software to change its
procedures, etc. is allowed. A site license agreement permits limited use
of the software. It protects the software by declaring it illegal to use
software outside the limits of the license.
Review Exercise 5.4
Fill in the Blank
a) People who committed cyber crime are classified as _______ and
_________.
b) The use of special hardware and software techniques to prevent the
illegal copying of software are known as ____________
c) To make copies of a software package for use at one site it needs to
have a ______________.
Short Answer
a) Define computer crime. Give two examples of computer crime.
b) The stealing of designs and trade secrets is called_____.
c) Explain what is meant by the following Copyright and Copy
protection?
d) Explain what is meant by site licensing
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5.5 Computer Security
Computer security is very important because there are a number of ways
computer systems and data can be compromised. It‟s concerned with
protecting information, hardware and software from unauthorized use as
well as from damage, intrusions, sabotage, and natural disasters. Some
ways of protecting computers are through encryption, restricting access,
anticipating disasters, and backing up data.
Encryption
Figure 5.5a Encrypting Message
Whenever information is sent over a network, there is always a
possibility that this information will be accessed without authorization.
The longer the distance travelled, the higher the security risk. One way to
protect sensitive data and information is to encrypt it. Encryption is the
process of converting readable data into unreadable characters. To read
the data, the recipient must decrypt it, or decipher it into readable form.
Some special log-in routines are voice and signature verification
systems. A voice verification system compares a person‟s live speech
with their stored voice pattern whereas signature verification system
recognizes the shape of your handwritten signature, as well as measuring
the pressure exerted and the motion used to write the signature.
Restricting Access
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A password is a unique combination of characters, such as letters of the
alphabet or numbers which identifies and allows access to certain
computer resources. Longer and mixed (alphabets plus numbers)
passwords provide greater security than shorter ones. A username, or
user ID, is a unique combination of characters, such as letters of the
alphabet or numbers that identifies a specific user.
Figure 5.5b password protection
A possessed object is any item that
you carry to gain access to a
computer facility. An example of a
possessed object is a smart card like
an ATM card. To use a possessed
object, you will need a personal
Identification number (PIN), which
is a numeric password, either
assigned by a company or selected
Figure 5.5c Card Access security
by the user.
Biometric security devices and systemssystem
include fingerprint scanners, face
recognition systems, voice verification systems and iris recognition
systems. The Biometric devices are becoming more popular because they
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are a nearly perfect method of identification and authentication. With a
callback system, a user connects to a computer only after the computer
calls that user back at a previously established telephone number.
Figure 5.5d biometric devices – Fingerprint scanner (left)& retinal scan
(right)
A firewall is a security
system
consisting
of
hardware or software that
prevents
unauthorized
access to data, information,
and storage media on a
network. Most companies
use firewalls to deny
network access to outsiders
and to restrict employees‟
access to sensitive data
such
as
payroll
or
personnel records.
Figure 5.5e Firewall
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Anticipating Disasters
Companies and individuals should prepare themselves for disasters.
Physical security involves protecting hardware from possible human and
natural disasters. This includes keeping hardware behind locked doors,
locking equipment to a desk or floor etc. Data security involves
protecting software and data from unauthorized tampering or damage.
Backing up Data
Equipments can be replaced. A company‟s data however may be
irreplaceable therefore it is a very important procedure is to back-up data,
that is, to make frequent back-ups or copies of data and to store them in
safe remote places.
The harmless intrusion of a hacker into an organizations computer
system can help the organization by identifying the weaknesses or
loopholes in its security system.
Revision Exercise 5.5
Fill in the blank
a) An example of biometric security device is called_____
b) Most companies use ________to deny network access to outsiders
c) _____________ are more secured than the ___________
Short Answer
a) List the security measures that can be used to prevent
b) Computer crimes
c) Explain how an organization can benefit from a hacker‟s harmless
intrusion into a computer system.
d) What do you understand by the term encryption process?
e) In your own words, explain “username & password”
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5.6 The Computer Virus
A computer virus is a damaging computer program that affects, or
infects, your computer negatively by changing the way the computer
works without your permission. Viruses are programs that migrate
through networks of networks (internet) via operating systems, most of
these viruses attached to different files, programs and websites. Once a
virus is in your computer, it can spread throughout and may damage your
files and operating system. The rise in use of networks, for example, the
internet and emails has increased the spread of computer viruses. Viruses
are activated on your computer in three basic ways:
Ways in which Viruses can be activated on your computer
Opening an infected file
Running an infected program
Using infected flash drives to transfer files to and from your computer.
Table 5.6 Virus activation
Today the most common way which computers become infected with
viruses is through e-mail attachments. Some viruses are harmless pranks
that simply freeze a computer temporarily or display sounds or messages.
Other viruses destroy or corrupt data stored on the hard disk. The
following signs might indicate that your computer has a virus.
a. An unusual message or graphical image displays on the computer
screen abruptly and continually.
b. An unusual sound or music plays randomly.
c. The available memory is less than what should be available.
d. A program or file suddenly is missing.
e. An unknown program or file mysteriously appears.
f. The size of a file changes without explanation.
g. A file becomes corrupted.
h. A program does not work properly.
Types of computer viruses
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A boot sector virus, sometimes called a system virus, appears when a
computer boots up. The system virus resides in the master boot record of
a hard disk.
A file virus, sometimes called a program virus, attaches itself to program
files. When you run the infected program, the virus is loaded into the
memory. Macro virus uses the macro language of an application, such as
word processing or spreadsheet, to hide virus code. With this type of
virus it only transfers, when a document tends to be open without
scanning its files, folder or even the USB in which the file has been
saved onto it.
The logic bomb is a virus that activates when it detects a certain
condition. For example, an angry worker planted a logic bomb in the
computers in his company and it began to destroy files when his name
appeared on the list of terminated employees. Another type of logic
bomb that activates on a particular date is called Time bomb viruses that
can stay hidden in your computer and is activated by a certain event in
time when the computer clock reaches this date. Hackers usually use
dates like Halloween, April fool‟s Day, etc., to activate a time bomb.
In addition to this, no matter how careful you might be, chances are, at
one time or another, you will find your computer infected with a virus. If
you are a frequent Internet user and you often download visual images,
music, videos from the internet and other files from online, so the
chances of you picking up Trojan horse, Worm and Malware are
almost certain.
Worm is a malicious program or malware that copies itself repeatedly in
memory or on a disk drive until no memory or disk space remains. When
no memory or disk space remains, the computer stops working. Some
worm programs even copy themselves to other computers on a network.
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Trojan horse is a wicked program under the guise of a legitimate
program on a bulletin board system. When the program is downloaded
for use it does damage to the hard disk, data or programs that are already
in the computer. Trojan horses are normally transferred as email
attachments.
The Multi-Headed Virus is one of the wicked bugs on the whole Internet.
Not only are there parts of this virus that will attach themselves to .exe
files on your computer, but it will also affect your computer‟s start up so
that you begin running the virus every time you turn your computer on
automatically.
A Cloning Virus is an old fashioned type of bug that quickly creates
duplicates for .exe files you have on your computer. The Author Virus
usually attaches itself to a program and then runs when you run that
program; on the other hand, it finds an .exe file, it actually deletes and
rewrites code so that the program is changed. Few common computer
viruses run this way since the level of virus needs to be so sophisticated.
Virus Detection & Removal
There is no completely effective method which exists to ensure that a
computer is safe from computer viruses and other malware. You can
however take several precautions to protect your home & work
computers from these infections. The most common way to protect your
computers from viruses is to install an antivirus program.
An antivirus program protects a computer against viruses by identifying
and removing any viruses found in memory or storage media or an
incoming file. Most antivirus programs also protect against worms and
Trojan horses. It automatically scans files you download from the Web,
e-mail attachments, files you open and all removable disks you insert
into the computer. One technique the antivirus programs use to identify a
virus is to look for virus signatures. A virus signature, also called a virus
definition, is a known specific pattern of virus code. It is always
necessary to update your antivirus program signature file as often as
possible to ensure these files contain patterns for newly discovered
viruses.
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Other measures that can be taken to prevent the spread of computer virus
& minimize damage are:
a. Make back-up copies of your data on a frequent basis.
b. Scan the back-up programs to ensure that it is virus free.
c. Avoid downloading computer games and music from unknown sites,
but if you are downloading a program, check that it does not have a
virus.
d. Do not open e-mail attachments unless it is from a trusted source.
Scan all email attachments you intend to open & delete attachments
that may be infected with a virus.
e. Limit your use of shareware programs.
f. Do not use pirated software on your computer.
Revision Exercise 5.6
Fill in the Blank
a)
An________________ protects a computer against viruses by
identifying and removing any viruses found in memory.
b) __________________ computer virus to ever hit the Internet
c) The most difficult kind of bug to detect and the most difficult to stop
are called _______________.
Short Answer
a) Define a computer virus.
b) Briefly outline how a virus spreads.
c) Explain a harmful action of viruses.
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5.7 Summary
1. The Internet, also called the Net, is a worldwide collection of
networks that links millions of businesses, government agencies,
educational institutions and individuals.
2. The computerization of society refers broadly to the widespread use
of computers, which has led to the restructuring of many functions
in society.
3. Information has become an invaluable asset for both individuals and
organizations. Computer Ethics are guidelines for the morally
acceptable use of computers in our society or the standard behavior
regarding the use of computers for individuals and organizations.
4. Computer crime it involves the use of computer and software for
illegal purpose. Computer crime takes many forms, from
unintentional disruption to vengeful acts to embezzlement.
5. Computer security is very important because there are a number of
ways computer systems and data can be compromised. It‟s
concerned with protecting information, hardware and software from
unauthorized use as well as from damage, intrusions, sabotage, and
natural disasters.
6. A computer virus is a damaging computer program that affects, or
infects, your computer negatively by changing the way the computer
works without your permission.
Key Terms
Economic trend
Technological Trend
Computer Aided Design
Artificial Intelligence
Expert Systems
Hackers
Computer Ethics
Encryption
Computer Crime
Time Stealing
Industrial Espionage
Data Stealing
Crackers
Site License
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Trap Door
Trojan horse
Copyright Ownership
Shareware
Computer Security
Computer Virus
Virus Signature
Physical Security
Time Bomb
Software Privacy
Copy Protection
Automated Larceny
Encryption
Malware
Firewall
Data Security
Review Questions – Multiple Choice
1. The standard of moral conduct that control how computer are used
are called
a. Ethics.
b. Laws.
c. Security requirements.
d. Business demands.
2. The issues that deal with the collection and use of data about
individuals is
a. Access.
b. Property.
c. Accuracy.
d. Privacy.
3. Identify theft is the impersonation by
a. thief of someone with a large bank account.
b. a thief of someone with computer skills.
c. a thief of someone with good credit.
d. a thief of someone‟s identity for the purpose of economic gain.
4. Gaining unauthorized access to a computer system would fall under
which category of computer crime?
a. Theft of services
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b. Hacking
c. Data Theft
d. Destruction of Data and Software
5. Intercepting personal communications, such as mobile calls is known
as
a. Computer monitoring.
b. Electronic eavesdropping.
c. Reverse engineering.
d. Hacking.
6. The main purpose of data protection is to
a. protect personal privacy.
b. prevent viruses.
c. reduce project failures.
d. increase the security of computer systems.
7. People who gain unauthorized access for the fun of it, but do not
intentionally do damage, are
a. employees.
b. hackers.
c. outside users.
d. members of organized crime.
8. ________commit the majority of computer crimes.
a. Employees
b. Hackers
c. Outside users
d. Members of organized crime
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9. Which statement best describes a worm?
a. A virus that is designed to destroy your hard drive.
b. A virus that is designed to frighten people about a nonexistent
virus.
c. A virus that doesn‟t need to attach itself to programs and
databases.
d. A virus that is designed to shut down a server.
10. A _______ act as a security buffer between a company‟s private
network and all extended networks.
a. Firewall
b. Password
c. Disaster recovery plan
d. Virus checker
11. Which of the following would best fir the following description –
software is copied and given to a friend without the permission of the
copy right owner?
a. Freeware
b. Piracy
c. Shareware
d. Public domain.
12. Having a(n) __ is important to help large organizations continue
operating until normal computer operations can be restored.
a. Firewall protection scheme
b. Encryption coding process
c. Disaster recovery plan
d. Virus encryption programs.
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Review Questions – Short Answers
1. Discuss how economic and technological trends have led to the
widespread use of computers.
2. Identify factors which should be considered in designing an
automated office.
3. Briefly describe the use of computers in the following areas:
a. special education
b. entertainment
c. research
d. voice recognition
e. wheel chair
f. slow learners
4. Identify the human senses that robots are capable of simulating best
5. Identify the human senses which robots are least capable of
simulating.
6. Define computer crimes.
7. List four reasons why it is difficult to detect computer crime.
8. Describe a software approach to copy protection.
9. Compare the form of legal protection given to software through
copyright laws with that given through a license agreement.
10. Explain how a virus spreads
Review Questions – Research Questions
1. Give reasons why the cybercriminal in the above case study was on
the rise.
2. Is there any proactive measure to address the increase of cybercrimes
in Fiji?
3. List at least 2 resources that Fiji should equip them with to combat
the increase in cybercrimes. Suggest how these resources can be
obtained.
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Additional Readings
Andrew Sears and Julie A. Jacko (Eds.). (2007). Human-Computer
Interaction Handbook (2nd Edition). CRC Press. ISBN 0-8058-5870-9
Julie A. Jacko and Andrew Sears (Eds.). (2003). Human-Computer
Interaction Handbook. Mahwah: Lawrence Erlbaum & Associates. ISBN
0-8058-4468-6
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition.
McGraw
Hill,
New
York,
2011.
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Chapter 6
Programming
Being a programmer means you never stop
learning. The environment we work in is constantly
changing, evolving so we have to keep up with the
changes.
After completing this chapter, you will be able to:
1. Differentiate between low level language and high level
language.
2. Describe the six steps involved in programming.
3. Discuss design tools including algorithm, pseudo code,
flowcharts and logic structures.
4. Explain what is meant by BASIC commands and BASIC
Keywords when used within a program.
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6.0 Introduction
What is a Program?
A program is a set of instructions for the computer to follow to
accomplish the task of processing data into information. It is prepared by
first formulating a task and then expressing it in an appropriate computer
language that is suited to the application. The specification is translated,
into a coded program directly executable by the computer on which the
task is to be run. The coded program is said to be in machine language,
while languages suitable for original formulation are called problemoriented languages. A wide array of problem-oriented languages has
been developed, some of the common ones being BASIC (Beginner‟s
All-Purpose Symbolic Instruction Code), Pascal, C++, Java, HTML and
XML.
BASIC is suited to both beginners and experienced programmers. Users
and the computer communicate with each other directly during the
writing and running of the program.
Pascal is a popular language in science and educational programs.
Encourage the use of structured programming techniques. Also provides
for data lengths of any length and size and works well with graphics.
C/C++ is general-purpose program that works with all types of
computers. Used in writing operating systems and databases as well as
some scientific applications.
Java is a general-purpose, concurrent, class-based, object-oriented
language that is specifically designed to have as few
implementation dependencies as possible. It is intended to let
application developers "write once, run anywhere.", meaning that
code that runs on Windows does not need to be edited to run on a
Mac. Java is currently one of the most popular programming
languages in use, particularly for client-server web applications
(Wikipedia).
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Programming
6.1 Generations of Programming Languages
Languages are described as occurring in "generations," from machine
languages to natural languages.
Computer professionals talk about levels or generations of programming
languages, ranging from "low" to "high." Programming languages are
called lower level when they are closer to the language the computer
itself uses. The computer understands the 0‟s and 1‟s that makeup bits
and bytes. Programming languages are called higher level when they are
closer to the language humans use - that is, for English speakers, more
like English.
There are five generations of programming languages. These are
1. machine languages
2. assembly languages
3. procedural languages
4. problem-oriented languages
5. natural languages.
Machine Languages: The First Generation
We mentioned earlier that a byte is made up of bits, consisting of 0‟s and
1‟s. These 0‟s and 1‟s may correspond to electric current being on or off
in the computer. They may also correspond to a magnetic charge's being
present or absent on storage media such as disk or tape. From these twostate system, coding schemes are designed that allow us to construct
letters, numbers, punctuation marks, and other special characters.
Examples of these coding schemes are ASCII, EBCDIC and Unicode.
Data represented in 0‟s and 1‟s is said to be written in machine language.
Assembly Languages: The Second Generation
Assembly languages have a clear advantage over the 0‟s and 1‟s of
machine language because they use abbreviations or mnemonics. These
are easier for human beings to remember. The machine language code
we gave above could be expressed in assembly language as
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163
ADD 210 (8, 13), 028 (4, 7)
This is still pretty obscure, of course, and so assembly language is also
considered low-level.
Assembly languages also vary from computer to computer. An assembler
converts these mnemonics to machine language. With the third
generation, we advance to high-level languages, many of which are
considered portable. That is, they can be run on more than one type of
computer – they are "portable" from one machine to another.
High-Level Procedural Languages: The Third Generation
People are able to understand languages that are more like their own
(e.g., English) than machine languages or assembly languages. These
more English-like programming languages are called "high-level"
languages. However, most people still require some training in order to
use higher-level languages. This is particularly true of procedural
languages.
Procedural languages are programming languages with like BASIC,
Pascal, C, COBOL, and FORTRAN. They are called "procedural"
because they are designed to express the logic - the procedures that can
solve general problems. Procedural languages then are intended to solve
general problems. COBOL, for instance, is used in all kinds of business
applications, such as payroll and inventory control. It is fourthgeneration languages, discussed later, that are intended to solve specific
problems.
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Programming
Compilers and Interpreters
For a procedural language to work on a computer, it must be translated
into machine language so that the computer understands it. Depending on
the language, this translation is performed by either a compiler or an
interpreter.
A compiler converts the programmer's procedural language program,
called the source code, into a machine language code, called the object
code. This object code can then be saved and run later. Examples of
procedural languages using compilers are the standard versions of
Pascal, C, C++ and Java.
An interpreter converts the procedural language one statement at a time
into machine code just before it is to be executed. No object code is
saved. An example of a procedural language using an interpreter is the
standard version of BASIC, VB Script, Perl and Python.
What is the difference between using a compiler and using an
interpreter?
When a program is run, the compiler requires two steps. The first step is
to convert entire the program's source code to object code. The second
step is to run the object code. The interpreter, in contrast, converts and
runs the program one line at a time. The advantage of a compiler
language is that once the object code has been obtained, the program
executes faster. The advantage of an interpreter language is that
programs are easier to develop.
Problem-Oriented Languages: The Fourth Generation
Third-generation languages are valuable, but they require training in
programming. Problem-Oriented languages, also known as very high
level languages, require little special training on the part of the user.
Unlike general-purpose-languages, problem-oriented languages are
designed to solve specific problems.
Natural Languages: The Fifth Generation
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165
Natural languages are still being developed. They are designed to give
people a more human (“natural”) connection with computers. The
languages are human languages: such as English, Hindi, Japanese etc.
Researchers also hope that natural languages will enable a computer to
learn “remember” information, as people do, and to improve upon it.
Clearly, this area is extremely challenging.
Discovery Learning:
What are the advantages of high level language over low level
language?
http://en.wikipedia.org/wiki/List_of_programming_languages_by_catego
ry gives a list of all programming languages by category.
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Programming
6.2 Program Planning
Once you have identified the programming language you will use to
develop your software, you must create a plan. There are six major steps
in creating software.
Step 1 Program Specification
Program specification is also called definition or program. In this step
the objectives, outputs, inputs, and processing requirements are
determined. These are as follows
Task
1
2
3
4
5
Description
Specify objectives
Specify outputs
Determine the required inputs
Define processing requirements
Document Specifications
Step 2 Program Design
In this step, a program is created using programming techniques such as
top down program design, pseudo code, flowcharts and logic structures.
An algorithm is a sequence of steps determined before writing the actual
code. An algorithm shows how to solve a problem and the procedure to
be followed.
Example of an algorithm
1. Start
2. Enter three numbers
3. Find total
4. Calculate average
5. Display output
6. End
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167
An algorithm can be expressed in different ways for example; the above
example is expressed in English.
Another technique called pseudo code (pronounced “soo-doo-code”) is
rapidly increasing in popularity. Also known as Structured English,
allows a programmer to use English like sentences to write an
explanations of what the program is supposed to do. The programmer
uses certain keywords in much the same manner as if writing in a
structured programming language. In short a pseudo code is an outline
of the logic of the program you will write.
Example of a pseudo code
10 Display enter three numbers
15 Input three numbers
20 Calculate Total = Number 1 + Number 2 + Number 3
25 Calculate Average = Total/ 3
30 Display Total and Average
35 End of Program
Program Flowcharts
A flowchart is a diagrammatic representation of a program or a graphic
representation of the steps needed to solve the programming problem. A
flowchart is an outline that depicts (shows) events or actions and the
sequence in which the actions must be taken to correctly solve the
problem.
Discovery Learning:
Write the steps for making Noodles and cakes. Basically you will be
writing two separate algorithms. Construct a flow chart for each of
these algorithms.
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Programming
Flowchart Symbols
Explanation
Begin/End
Indicated the beginning and end of a
program.
Indicates that a calculation should be
performed or assigning a value to a
variable.
Indicates an input/read or an output
operation.
Process
Input/Output
Allows alternate courses of action
based on a condition. A decision
indicates a question that can be
answered as yes or no or (true or
false).
Decision
Is used to eliminate lengthy flow lines.
Its use indicates that one symbol is
connected to another.
Connector
FOR…NEXT – the hexagon is used
to display the FOR…NEXT statement
and any other loops. These loops are
also referred to as iteration statements.
For……Next
Indicates the order in which operations
should be performed.
Flowlines
Table 6.1a Flow chart symbols
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Logic Structures
Three arrangements are used in programming to write structured
programs. The three logic structures are:
a. Sequence Structure
b. Selection Structure
c. Iteration (Loop) Structure
Sequence Structure
In the sequence structure one program statement follows another. There
are no decisions to be made the boxes logically follow one another.
Enter 3 numbers
Add three numbers
Find the average
Display average
Figure 6.2b Sequence structure
Selection Structure
The selection structure represents a choice. It occurs when a choice must
be made. The outcome of this structure offers two (2) paths to follow
when a decision must be made by a program. If…then…else structure is
used to determine which of the two available actions to chose depending
on whether a condition evaluates to true or false.
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Programming
Is it
Raining
?
y
e
s
Watch Movie
n
o
Play Netball
Figure 6.2c Selection structure
Iteration (Loop) Structure
The loop/ iteration structure describes a process that may be repeated as
long as a certain condition remains true. The process will loop/ iterate as
long as the condition requires it to.
For (statement)
Statement to be
executed
(CONDITION)
Figure 6.2d Loop structure
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171
START
A=9
B=7
C=A+B
Display C
END
Figure 6.2e Example of a flow chart
Step 3 Program Coding
Coding is the actual writing of the program using a programming language.
Here you use the logic you developed in step 2 (Program Design) to
actually write the program.
Step 4 Program Testing
Testing a program and correcting syntax and logic errors is called
debugging. There are three types of programming errors.
1. A syntax error is the violation of the rules or syntax of the
programming language. (Example misspelling of keywords).
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Programming
2. A logical error occurs when a programmer uses an incorrect
calculation or leaves out an important programming process.
Example a payroll program that does not compute overtime
hours has a logical error.
3. A Run time error usually occurs when a programs tries to
perform invalid operations such as division by zero, or
referencing a file that does not exist.
Testing Process
Several methods have been devised for finding and removing syntax and
logical errors. They are as follows:
a.
b.
c.
d.
e.
Desk checking
Manual Testing with sample data
Attempt at translation
Testing sample data on the computer
Testing by a select group of potential users (skilled)
Desk Checking is done by a programmer sitting at a desk who checks
(proof reads) a printout of the program. He goes through the listing line
by line looking for syntax and logic errors and making the necessary
corrections.
Manual Testing with Sample Data is where both correct and incorrect
data is run through the program manually to test for correct processing
results.
Attempt at Translation is where the program is run through a computer
using a translator program (compiler or interpreter). The translator
attempts to translate the written program from the programming
language into machine language. Before the program is run, it must be
free of syntax errors. Syntax errors will be identified by the translator or
compiler and the program compilation will be terminated.
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Testing Sample Data on the Computer is done when all syntax errors
have been corrected, the program is tested for logic errors. Sample data
is used to test the correct execution of each program statement to check if
the correct outputs are delivered by the program. With sample data, you
have the output/results calculated manually before it is fed into the
program and then compare with what the program gives as output.
Testing by a Select Group of Potential Users is sometimes called beta
testing. This is usually the final step in testing a program. Here, potential
users (skilled) tryout the program and provide feedback. These feedbacks
are then used by the programmer to make those important and final
changes to the program.
Step 5 Program Documentation
Documenting is writing description of the purpose and process of the
program. Documentation consists of written descriptions and procedures
about a program and how to use it. It not something that is done just at
the end of the programming process but is rather an ongoing process
through all programming steps. In this step, all prior documentation is
reviewed and finalized. Documentation is important for all people who
may be involved with the program in the future.
There are two types of documentation.
User manual describes how to use the program to the novice user.
Program documentation describes the major processes with the program
for future modifications and upgrades. These are usually called
comments or remarks with the source code.
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Step 6 Program Maintenance
Programmers update software to correct errors, improve usability,
standardize and adjust to organizational changes. The final step of the
programming life cycle is program maintenance.
The purpose of program maintenance is to ensure that the current
programs are operating error-free, efficiently and effectively. Activities
in this area fall in two categories:
1. Operations – make the programs user friendly so that it is easily
understood by new employees.
2. Changing needs – is inevitable since organizational needs and
business processes change over time.
Review Exercises 6.2
1. Write an algorithm and draw a flowchart to make a cup of coffee.
2. Write an algorithm and draw a flowchart showing how you spent a
typical day during your school holidays.
3. Draw a flowchart to find the sum of two numbers and display the sum.
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6.3 QBASIC Language
QBASIC (stands for Quick Beginner's All Purpose Symbolic Instruction
Code) was written (invented) in 1963, at Dartmouth College, by
mathematicians John George Kemeny and Tom Kurtz as a teaching tool
for undergraduates. BASIC has been one of the most commonly used
computer programming languages, a simple computer language
considered an easy step for students to learn before more powerful
languages such as FORTRAN at that time.
QBASIC was initially designed to be a very concise language with limited
capabilities. The intent was to have a programming language that could be
learnt quickly, so that students, with a limited amount of instructions could
write programs and utilise the computer as tool for problem solving.
The primary advantage of QBASIC is its ease of use. Part of the ease of
use, of course is because of its somewhat limited capabilities. In recent
years, however, with extensions to the language, QBASIC has become a
more powerful language. The extensions have included the ability to
create and access sequential and random files and the ability to create
graphics.
As the extensions were added to the language many minicomputers
manufacturers began utilising QBASIC for business application
programming. Thus, today, BASIC is used extensively on minicomputers
for business programming as well as being the primary language of PC's.
The Structure of QBASIC Program consists of a series of statements
consisting three parts.
10 PRINT “Welcome to BASIC”
Line
Number
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Keyword
Remainder of Statement
Programming
Rules for writing codes in QBASIC
1. The beginning of any statement is always done by a line number
which should be an integer. Example1, 2, 10, 100 etc. Neither a
decimal nor a negative number can be used as a line number.
2. Line numbers are always used in ascending order.
3. The line numbers range from 1 to 99999.
4. It is convenient to number lines in order of 10‟s like 10, 20, and 30
so that you have room for additional lines.
5. After the line number, the statement should begin with the key word
called command line such as LET, READ, DATA, INPUT, and
PRINT etc.
6. More than one statement cannot be written on one single line.
QBASIC Commands
Commands Description
Is simply used to erase a line number.
Delete
Allows the user to modify certain line written in a BASIC
Edit
program.
LIST BASIC program files stored on disk.
Files
Display a BASIC program on the screen.
List
Print a BASIC program using a printer.
LList
Retrieve a specified BASIC program from the disk.
Load
Renumber certain lines within BASIC program.
Renum
Execute a BASIC program.
Run
To save a BASIC program into disk.
Save
Allows the user to get out of the BASIC programming
System
environment and BASIC to DOS or to a menu system.
Table 6.3a QBASIC commands
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QBASIC Keywords (used when writing programs)
Keywords Description
Clears the screen and positions the cursor in the upper
CLS
left hand corner.
Terminates the execution of the program, and tells the
END
computer system that there are no more statements in the
program.
Used together to create loops in a program.
FOR
NEXT
GOSUB... Used to branch to a subroutine then return the control to
RETURN the point in the program where the branch was executed.
To branch to any part of the program during execution.
GOTO
This will contain a list of variables.
READ
Contains a list of data elements.
DATA
Causes the program to branch to another line number
IF...
only if certain conditions are true, otherwise the
THEN
computer ignores the statement and proceeds to the next
ELSE
statement in the program.
Accepts data directly from the terminal during execution.
INPUT
Used to assign or define a variable to be equal to an
LET
expression.
Used to display output.
PRINT
Permits a programmer to document a program by
REM
including remarks.
The DIM (for Dimension) statement instructs the
DIM
compiler or interpreter to set aside a certain amount of
memory space for array. The DIM statement must
appear at the beginning of the program and may allocate
space for several arrays. An array is a sequence or list of
items arranged in some meaningful ordered pattern. An
array can be visualised as a row of numbered boxes, each
holding a value.
Table 6.3b QBASIC keywords
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Programming
Review Exercise 6.3
1. Draw a flowchart and write a program to calculate the area of a
triangle with base 12 and height 10.
2. Draw a flowchart and write a program to calculate the area of a circle
with radius 6.
3. Draw a flowchart and write a program and to calculate simple
interest where Principle = $66000, interest rate = 7.99% and time =
18 years.
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6.4 Data Types, Variables and Operators
Data Types
Integer Numbers are whole numbers, such as 1, 250, -17, etc. They do not
have a decimal point and may be preceded by a '+' or '-' sign. In Basic,
integers are never written in commas.
Real Numbers are numbers that have a decimal point, such as 1.5, 2.334, 17.324 and maybe preceded by a '+', or '-' sign.
Exponential format is a way of expressing numbers that are very large or
very small. In general, numbers in may contain up to 7 to 9 significant
digits.
A constant may be a character. Character constants or strings are letters,
numbers, spaces and special characters (such as $, %, &, ?, (, ), <, >).
Character strings are often used for titles, labels and printed reports.



Character strings are enclosed in quotation marks.
 "ABC"
"Hello James, how are you?"
 "1.23"
"10%"
A character string may contain from 0 to 255 characters.
A double quote is represented in a character string.
Variables
A variable is a space created in the memory to hold a value that is used by
the program and is likely to change.
Numeric variable holds numeric values, such as numbers. When you refer
to a program but do not assign it a value, Q BASIC will set the value of the
variable to 0.
A constant variable stores a value that remains fixed throughout the
execution of the program. For instance rather, asking the user to enter the
value for pi, you can create a constant variable named pi =3.141592654.
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Programming
String Variable hold character string values, such as letters and words. A
typical string variable can hold from 0 to 255 characters, depending upon
the particular versions of Basic.
Variables are named and constructed according to simple rules.


The name of a numeric variable must always start with an alphabet
(can be just one alphabet) and then followed by other letters or even
numbers. For example: SUM, NUM, AGE, X, Y, A1, B5, STREET6.
The name of a string variable is the same as a numeric variable but a
dollar sign ($) must be included at the end of the name. For example:
LName$, FName$, Status$, PO$, Z9$, L3$.
You may use a period (.) inside a name to make easier to read or use an
underscore (_), for example: L_Name$, F.Name$.
Best practice: when naming variables, use naming conventions which
simply means, give names to variables that are meaningful and easily
understood. For example, instead of just using plain X, Y, Z, name them
like Num1, Num2 and Num3 respectively. This is very important when
writing big programs. The name of the variable should itself suggest what
type of value it holds.
Operators
Arithmetic Operators in QBASIC
Operator
Operation
Expression
Comment
^
*
/
+
-
Exponentiation
Multiplication
Division
Addition
Subtraction
6^2
3*4
36/4
7+3
10-5
62
3x4
36÷4
7+3
10-5
Table 6.4a Order of Operation follow BEDMAS
Relational and Logical Operators have a specific order of Precedence.
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181
QBASIC evaluates relational and logical operators in a specific order.
The following table shows the priorities (order of precedence) of these
operators.
Operation
Priority
Association
Grouping ( )
1
N/A
^ or
2
Left to right
NOT
3
N/A
* and /
4
Left to right
+ and -
5
Left to right
<, <=, =, <>, >, >=
6
N/A
AND
7
Left to right
OR
8
Left to right
Table 6.4b Order of precedence for logical operators
Review Exercise 6.4
Write the following arithmetic expressions into its equivalent QBASIC
form.
1.
XY
2.
3(X + Y)
3.
4.
3(X + Y) (X - Y)
5.
X
Y
6.
(X + Y)2
7.
X+Y
8.
X(-Y)2
10.
AX2 + BX + C
Z
9.
X+Y
Z+W
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Programming
X+Y
6.5 Keywords in QBASIC
6.5.1 The PRINT Statement
In QBASIC the PRINT Statement is used to display output. Figure 6.5.1a
shows how PRINT statements display numeric values in the output
window while Figure 6.5.1b shows how PRINT statements display
strings in the output window.
10 PRINT 100
20 PRINT 213
30 PRINT -314, 56
40 END
100
213
-314
56
Figure 6.5.1a Program (left) & output (right)
10 PRINT “FIJI SCHOOL LEAVING CERTIFICATE”
20 PRINT “COMPUTER STUDIES”
30 END
FIJI SCHOOL LEAVING CERTIFICATE
COMPUTER STUDIES
Figure 6.5.1b Program (top) & output (bottom)
The PRINT statement is also used to display values stored in each
variable as shown in Figure 6.5.1c.
10 LET Num1 = 45
20 LET Num2 = 21
30 PRINT Num1, Num2
40 END
45
21
Figure 6.5.1c Program (left) & output (right)
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183
Take note of the following:
1. If a PRINT statement ends with a comma (,) or semicolon (;) the
next PRINT statement will be continued on the same line in the
output window.
2. Semicolon in the PRINT statement causes each item in the output to
be printed immediately (no space) after the preceding ones.
3. Comma in the PRINT statement causes each item in the output to be
printed at the beginning of each print zone (each print zone is 14
spaces wide) as shown in the outputs of Figures 6.5.1a and 6.5.1b.
Review Exercise 6.5.1
1. Determine the output for the following program.
10 PRINT “Welcome to Fiji”,
20 PRINT “Bula and Namaste!”
30 PRINT “Your Room # is: ”;
40 PRINT “679”
50 PRINT
60 PRINT “Enjoy your stay!!!”
70 END
2. Determine the output for the following program.
10 LET Num = 6
20 LET Num1 = Num * Num
30 PRINT “Number IS ”, Num
40 PRINT “Number SQUARED IS: ”, Num1
50 END
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Programming
6.5.2 The LET statement
The LET statement allows the programmer to assign a value to a variable.
For this reason it is called an assignment statement.
e.g
10 LET Num1 = 5
The LET statement can be used to assign a value of one variable to another
variable.
e.g
20 LET Num2 = Num1
In this assignment statement, the value stored in variable Num1 will be
assigned to the variable Num2. So now, Num2 also holds a value 5.
The LET statement can also be used to assign the result of a calculation to
a variable.
e.g
30 LET Total = Num1 + Num2
This statement will pull the values stored and variables Num1 and Num2
from the memory; add it and then store the result in the variable Total.
Therefore, value 10 is now stored in the variable Total.
Review Exercise 6.5.2
1. Write a LET statement that will assign your first name to a variable.
2. Using LET Statement, write a program that finds the average of the
numbers 3, 7, 10.
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185
3. Draw the flowchart and write a program that calculates the volume of
the box given below.
6 cm
3cm
4cm
4. Draw the flowchart and determine the output of the following
program.
10 LET X = 7
20 LET Y = 3
30 LET Sum = X + Y
40 PRINT Sum
50 LET Product = Y * Z
60 PRINT Product
70 PRINT X – Y
80 END
5. Write a program with CLS statement, ending with an END statement
and having one line for each step to calculate the price of an item
after a 30% reduction.
a. Assign the value 19.95 to the variable price.
b. Assign the value 30 to the variable discount.
c. Assign the value of discount divided by 100 and multiplied by
price to the variable markdown.
d. Assign the value in the variable new_price by subtracting
markdown from price.
e. Display the value of the variable new_price.
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Programming
6.5.3 The INPUT Statement
The INPUT statement allows the programmer to design programs that
can ask the user of the program to supply input/data for processing. The
INPUT statement signals the user to enter data and then assigns these
data to appropriate variables. The form of the INPUT statement is the
keyword INPUT followed by the name of the variable as shown below.
10 INPUT Variable_Name
The following program accepts input values for A, B and C and then
displays the values and their sum.
10 INPUT A
20 INPUT B
30 INPUT C
40 PRINT A,B,C
50 PRINT “The Sum of these numbers = ”; A + B + C
60 END
Figure 6.5.3a Program asking for three numeric inputs
In Figure 6.5.3a, the output window will just present a blinking underscore
cursor expecting the user to enter a value. There is no indication for the
user on what to do. As a programmer only you will be aware on what to
enter, but the main idea of writing programs is to design it to be user
friendly. One way to make your program user friendly is by using
appropriate prompts and display messages guiding the user throughout the
program.
Including prompts in INPUT statements
Normally an input statement has to follow a print statement which
displays a message which indicates to the user on what to enter as shown
in Figure 6.5.3b.
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187
10 PRINT “Please Enter Your Name”
20 Input N$
30 PRINT “Hello”, N$
40 END
Prompt
Please Enter Your Name
Zaheer
Hello Zaheer
User supplied input data
Figure 6.5.3b Using prompt with PRINT – program (top) & output
(bottom)
It is also possible to include a prompt in an INPUT Statement. The
message is separated from the Variable_Name by a semicolon. The
inclusion of the prompt in the INPUT Statement reduces the number of
lines in the program. The form of the prompt used with the INPUT
statement is shown below.
10 INPUT “Your Message/Prompt”; Variable_Name
The following program has a message prompt in the INPUT Statement
and allows the user to enter multiple variables.
10 INPUT “Enter your name and age”; Name$, Age
20 PRINT “Your name is” Name$; and your age is ”; Age
30 END
Enter your name and age? Shelvin
Your name isShelvin and your age is 16
16
Figure 6.5.3c Using prompt with INPUT– program (top) & output
(bottom)
Take note of the space
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Programming
Review Exercise 6.5.3
1. Write a program that asks the user to enter three values. The program
should then determine the sum, average and product of the three
numbers entered and displays them with appropriate labels.
2. Write a program that asks the user to enter his/her name, and
marks to English, Mathematics, and Computer. The program
should then calculate the total and the mean mark and displays
them with appropriate labels
NOTE: Both programs should be user friendly.
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189
6.6 Flow Control and Decision Making
6.6.1 Flow Control
A QBASIC program is read from left to right and top to bottom when
each line is executed after the previous one in numerical order.
However, this sequence of execution can be altered or stopped by
creating a branch or a loop. In QBASIC, the two statements that can do
this are the GOTO statement and the IF statement.
The GOTO statement creates a branch or a loop without any conditions
(unconditional branching). The GOTO statement is written with the
keyword GOTO followed by a line number as shown below.
20 GOTO Line Number
The GOTO Statement may branch to different parts of the program as
shown in Figure 6.6.1a
10 REM THIS IS A PROGRAM WITH GOTO STATEMENT
20 PRINT “THIS IS LINE 20”
30 GOTO 60
40 PRINT “THIS IS LINE 40”
50 GOTO 80
60 PRINT “THIS IS LINE 60”
70 GOTO 40
80 END
This is line 20
This is line 60
This is line 40
Figure 6.6.1a Using GOTO to jump between lines program (top) &
output (bottom)
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Programming
Creating Loops with GOTO Statement
This program accepts input and calculates squares unless the user
terminates the procedure, by adding a GOTO statement a loop is created.
10 INPUT I
20 J = I * I
30 PRINT I, “SQUARED IS”; J
40 GOTO 10
50 END
Figure 6.6.1b Loop with the GOTO statement
Problems with Loops
Although loops are useful, they can lead to problems if not structured
properly. One of the most common mistakes that programmers make is
the creation of the infinite loops. The program given in Figure 6.6.1 is an
infinite loop but can be terminated by the user. However, this kind of
design is not recommended. Figure 6.6.1c also shows an infinite loop.
10 INPUT I
20 PRINT I
30 I = I * I
40 PRINT I
50 GOTO 30
60 END
10 INPUT X
20 LET Y = X = 1
30 PRINT X, Y
40 GOTO 20
50 END
Figure 6.6.1b Infinite loop with the GOTO statement
The program in the right of Figure 6.6.1b uses the GOTO statement that
branches to statement 20 instead of the input statement and this creates an
infinite loop. As a result the program continues to display the two values
over and over until it is stopped/terminated manually.
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191
Review Exercise 6.6.1
Examine the following programs then answer the questions that follow.
1.
10 REM USE OF A GOTO STATEMENT
15 LET S = 100
20 INPUT N
25 LET S = S - N
30 PRINT S;
35 GOTO 25
RUN
a)
b)
c)
d)
Which statement(s) can be left out without affecting the program?
What was the initial value of S?
What value is assigned to N?
Write down the first 10 values of output as instructed by the
PRINT statement?
e) What command could you use to terminate the program?
f) Suppose the statement in line 35 was changed to GOTO 20. What
effect would this have on the program?
2. Consider the program given below and answer the following
questions.
10 A = 1
15 B = 2
20 PRINT A; B;
25 C = A + B
30 PRINT C;
35 A = B
40 B = C
45 GOTO 25
RUN
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Programming
a) What are the starting values of A, B, and C?
b) Explain the purpose of statement 35 and statement 40?
c) Write down the first 10 values of output as instructed by the print
statement?
d) Can you observe a pattern in the output? If so, what is it?
6.6.2 Decision Making
The IF...THEN statement
An important feature of a program is the ability to make decisions based
on certain conditions. The IF statement enables the program to either
perform or skip an action depending on whether a particular condition
has evaluated to true or false.
The program may be required to make comparisons between two values
and based on these comparisons, the next course of action is decided. If
the specified IF condition evaluates to true, then the THEN action is
executed. If the condition evaluates to false, the control passes to the
next line in the program. The form of the IF statement is shown below.
10 IF condition THEN action
The program given below in Figure 6.6.2a will display either one of the
following depending on what number the user enters.
If the number is greater than zero it only displays VALUE IS POSITVE.
If the number is less than zero it only displays VALUE IS NEGATIVE.
If the number is equal to zero it only displays VALUE IS ZERO.
NOTE: It is a good programming practice to move the statement
followed by THEN keyword and indent it. This makes it very easy to
follow your program.
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193
10 INPUT “ENTER A NUMBER”; VALUE
20 IF VALUE > 0 THEN
PRINT “VALUE IS POSITIVE”
30 IF VALUE < 0 THEN
PRINT “VALUE IS NEGATIVE”
40 IF VALUE = 0 THEN
PRINT “VALUE IS ZERO”
50 END
Figure 6.6.2a Using IF...THEN to check whether a number is positive,
negative or zero
The IF...THEN...ELSE Statement
The IF...THEN...ELSE statement operates in a similar way that the
IF...THEN operates, but includes a separate action to be performed if the
IF condition evaluates to false.
Consider this example: All people who are eligible to vote have to be
twenty one years or older otherwise they cannot vote.
Now consider the same example when written in a program given in
Figure 6.6.2b.
10 INPUT “Enter your age : ” AGE
20 IF AGE >= 21 THEN
PRINT “You are eligible to vote…”
ELSE
PRINT “You cannot vote…”
30 END
Figure 6.6.2b Using IF...THEN...ELSE to check whether a person is
eligible to vote or not
The otherwise part is always handled by the ELSE statement and is only
executed if the IF condition evaluates to false. If the IF condition
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Programming
evaluates to true, the ELSE statement is completely ignored. You do not
have to specify a condition for the ELSE statement.
Boolean Expressions
As you have already seen, a Boolean expression simply uses relational
and logical operators to describe a relationship between two or more
values. This expression is evaluated when the IF statement is executed to
see if the condition evaluates to true/false.
The table below describes the relational operators that can be used in
QBASIC programming.
Operator Description
>
greater than
<
less than
>=
greater than or equal to
<=
less than or equal to
<>
not equal to
=
equal to
Table 6.6.2a Relational Operators
Logical operators can be used to combine relational expressions to test
complex conditions. The three logical operators you can use in QBASIC
are AND, OR and NOT.

The logical operator AND is used to combine two or more relational
expressions (compound Boolean).
This compound Boolean
expression will only evaluate to true if all expressions evaluate to true.
As soon as one expression evaluates to false, the entire expression will
be evaluated to false.
For example, consider line 40 of the program as shown in Figure
6.6.2c.
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195
40 IF(Total_mark > 350) AND (Eng_mark >=60) THEN
PRINT “Scholarship Granted”
Figure 6.6.2c Evaluating compound Boolean expression
Now in this case the program will only display Scholarship Granted if
and only if both conditions are evaluated to true, meaning that both the
Total mark and English mark has to be greater than equal to 350 and
60 respectively.

The logical operator OR is also used to evaluate compound Boolean
expressions. The compound Boolean expression will evaluate to true
as long as one of the expression is evaluated to true. It will only
evaluate to false if and only if all expressions are false.
Considering the same example of line 40 from Figure 6.6.2c and
replace the keyword AND with the keyword OR.
Now in this case, the program will display Scholarship Granted for
every English mark that is greater than or equal to 60 even if the total
mark is less than 350. Likewise, it will display the same result if the
Total mark is greater than equal to 350 but failed English. You can
clearly see that only one expression needs to be true for the entire
Boolean expression to be evaluated as true. It will only evaluate to
false if both marks are less than the set criteria.

196
The logical operator NOT is used with a single expression. It
evaluates to true when the expression evaluates to false and false when
the expression is true.
Programming
Review Exercise 6.6.2
1. Draw the flowchart and determine the output for the two programs
given below.
10 INPUT “ENTER A
NUMBER”; X
20 IF X > = 18 THEN 60
30 IF X <= 7 THEN 70
40 LET X = X + 3
50 GOTO 70
60 LET X = X + 1
70 LET D = 2 * X
80 END
10 I = 10
20 I = I + 1
30 PRINT I
40 IF I < = 15 THEN 20
50 END
2. Consider the program shown below.
10 INPUT “ENTER TWO NUMBERS”; K, L
20 IF K = 1 AND L = 2 THEN 50
30 PRINT “TRY AGAIN”
40 GOTO 10
50 PRINT “GOOD TRY”
60 END
What will the output of the program if
i.
K = 5L = 6
ii.
K = 1L = 2
3. The Principal of a school needs a program that would help the school
Librarian to easily locate books in the Library. Draw a flowchart and
write a program that will enable a user to enter a book number and
get the location of the book displayed. Use the contents of the table
given to draw the flowchart and write the program.
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197
Book Number
1 – 200
Location
Row 1 Top shelve
201 – 500
Row 1 Bottom shelve
501 – 800
Row 3
801 – 1000
Row 4
4. Determine the output of the following program?
10 INPUT “ENTER THE VALUE”; VALUE
20 IF VALUE > 0 THEN 50
30 IF VALUE < 0 THEN 60
40 IF VALUE = 0 THEN 70
50 PRINT “VALUE IS POSITIVE”
55 GOTO 80
60 PRINT “VALUE IS NEGATIVE”
65 GOTO 80
70 PRINT “VALUE IS ZERO”
80 END
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Programming
6.7 Iteration (Loops) and Subroutine
6.7.1 Iteration
The FOR...NEXT Statement
In QBASIC simple loops can be created with to GOTO keyword. This
makes the program very weak and should not be used frequently. Instead
for creating a proper looping structure in your QBASIC program, use the
FOR...NEXT statement. The form of the FOR...NEXT statement is given
below.
FOR Loop_variable = start_value TO stop_value STEP Increment
…
statements
…
NEXT Loop_variable
The table given below shows how the FOR loop variable‟s (I) value is
controlled with the increment and decrement using the STEP keyword.
FOR Expression with variable I
Possible values for I
FOR I = 1 TO 5
1, 2, 3, 4, 5
FOR I = 10 TO 20 STEP 2
10,12,14,16,18,20
FOR I = 1 TO 10 STEP 3
1, 4, 7, 10
FOR I = 30 TO 20 STEP -2
30, 28, 26, 24, 22, 20
FOR I = 1 TO 50 STEP 10
1, 11, 21, 31, 41
Table 6.7.1 Controlling iterations in a FOR loop
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199
The FOR Statement is always used in conjunction with a NEXT
Statement. The NEXT statement indicates the number of statements
before it as part of the loop structure.
NOTE: It is a good programming practice to indent the statements that
are between the FOR statement and the NEXT statement. This makes it
very easy to follow your program.
10 FOR I = 1 to 5
20
PRINT “LOOP REPETITION”; I
30 NEXT I
40 PRINT “LOOP COMPLETED”
50 END
Loop Repetition 1
Loop Repetition 2
Loop Repetition 3
Loop Repetition 4
Loop Repetition 5
Loop Completed
Figure 6.7.1 FOR loop program (left) & output (right)
Review Exercise 6.7.1
1. Draw a flowchart for the program given in Figure 6.7.1.
2. Determine the output for the following programs.
a.
b.
10 LET X = 1
20 FOR I = 1 TO 3
30 LET X = X + 1
40 PRINT X
50 NEXT I
60 END
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Programming
10 FOR I = 1 to 2
20 PRINT “*”
30 FOR J = 1 TO 3
40 PRINT J
50 NEXT J
60 NEXT I
70 END
c.
10 FOR I = 1 TO 5
15 PRINT "*";
20 NEXT I
25 FOR J = 1 TO 7
30 PRINT "*";
35 NEXT J
40 FOR K = 1 TO 4
45 PRINT "*";
50 NEXT K
RUN
d. Write a program using FOR...NEXT statement to convert degrees
Fahrenheit to degrees Celsius using the following approximation
rule:
C = F/2-15
Starting Value = 32
Ending Value = 64
Increment = 4
The output should be printed as follows:
FAHRENHEIT
CELSIUS
32
1
36
...
40
...
...
...
...
...
64
17
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201
6.7.2 Subroutine
In QBASIC a subroutine is simply a group of lines that are branched and
executed and the control returned to the next line in the program where
the subroutine was initiated. This is done by GOSUB and RETURN
statements.
The form of the GOSUB...RETURN statement is given below.
10 GOSUB Line Number
.
.
.
100 RETURN
The GOSUB Statement is similar to GOTO Statement. However, when a
RETURN Statement is encountered, control is returned to the statement
following the GOSUB so that the program can continue execution as
shown in Figure 6.7.2.
10 GOSUB 400
20 GOSUB 400
30 GOSUB 400
40 END
400 PRINT “HOLIDAYS!!”
410 RETURN
HOLIDAYS!!
HOLIDAYS!!
HOLIDAYS!!
Figure 6.7.2 GOSUB...REUTRN program (left) & output (right)
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Programming
Review Exercise 6.7.2
Write the output for the following program.
10 GOSUB 600
20 PRINT “SUBMIT MY ASSIGNMENT”
30 GOSUB 800
40 GOTO 900
600 PRINT “I WILL”
610 RETURN
800 PRINT “TOMORROW MORNING”
810 RETURN
900 END
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203
6.8 Data, Library and Arrays
6.8.1 READ, DATA, RESTORE
The READ/DATA statement
The READ/DATA statement causes data to be read from the computer‟s
internal memory. READ does not stop the execution of the program
because it will retrieve data that is stored in the computer memory by the
DATA statement. The data in the data statement must be given in the
same order as the variables in the READ statement and must be
separated by commas. DATA statement can be placed anywhere in the
program. A READ command can access more than one DATA
statement. Figure 6.8.1a shows how the READ/DATA statements are
used.
10 READ A, B, C
20 DATA 3, 9, 2
30 LET SUM = A + B + C
40 PRINT A, B, C
50 PRINT SUM
60 END
3
3
14
9
9
2
2
Figure 6.8.1a READ/DATA program (left) & output (right)
The RESTORE statement
The RESTORE statement pulls the data from the DATA list and assigns it
to any other variables declared after the RESTORE statement as shown in
line 20 and line 30 of Figure 6.8.1b.
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Programming
10 READ A, S$, N$
20 RESTORE
30 READ A1. S1$, N1$
100 DATA 12, K, JAWEED
200 PRINT A, S$, N$
210 PRINT A1, S1$, N1$
500 END
12
12
K
K
JAWEED
JAWEED
Figure 6.8.1b READ/DATA & RESTORE program (right) & output (left)
Review Exercise 6.8.1
1. Determine the output for the following program.
10 READ A, B, C$
20 DATA 2, 3, “EXAM”
30 PRINT A, B, C$
40 END
2. Determine the output of the following program.
10 DATA 2, 3, 5, BASIC
20 READ B1, B2, B3, B1$, B2$
30 DATA “PROGRAMMING PRACTICE”
40 PRINT B1, B2, B3
50 PRINT B1$; “
“; B2$
100 END
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205
3. Determine the output and draw a flowchart for the following program.
10 READ A, B, C
20 IF A = 0 THEN 90
30 IF A > B THEN 50
40 GOTO 10
50 IF B > C THEN 70
60 GOTO 10
70 PRINT A; B; C
80 GOTO 10
90 DATA 5, 6, 7, 3, 3, 3, 3, 9, 8, 7, 0, 1
100 END
RUN
4. Determine the output for the following program.
10 READ X, Y, Z
20 DATA 2, 4, 6, 8, 10
30 RESTORE
40 READ A, B
50 PRINT X, Y, Z
60 PRINT A, B
70 END
5. For large quantity sales, Computer Professional Ltd charges $999.95
each for the first 10 computers ordered, $989.95 each for the next 10
computers and $979.95 each for any additional computers. Write a
program that will print a price list giving the total for purchase of any
number of computers from 1 to 40.
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Programming
6.8.2 Library Functions
In QBASIC, the library (built-in) functions are used to perform
frequently used calculations. The argument (can be a constant, a
variable, or an expression on which the function is to be performed) of
the library function is enclosed in parenthesis (brackets). There are two
types of functions in QBASIC. Table 6.8.2a summarises some common
mathematical functions and table 6.8.2b summarises some common
string functions. In table 6.8.2b, the argument G$ may be a string
variable, constant, or expression. R and N are variables, constants, or
expressions. The function whose names end with a $ return a string
value. The other functions return a numeric value.
Function
SQR(arg)
Purpose
Calculate the square root of the argument. The argument
must be positive.
SIN(arg) Calculates the sine of the argument. The argument must
be expressed in radians.
COS(arg) Calculates the cosine of the argument. The argument must
be in radians.
TAN(arg) Calculates the tangent of the argument. The argument
must be in radians.
ATN(arg) Calculates the arctangent of the argument. The argument
must be in radians.
LOG(arg) Calculates the natural logarithm (base e) of the argument.
EXP(arg) Raises e to the power designated by the argument.
INT(arg) Determines the largest integer not greater than the
argument.
ABS(arg) Calculates the absolute value of the argument.
SGN(arg) Determines the sign of the argument. (-1 if the argument is
negative; 0 if the argument is 0; +1 if the argument is
positive).
Table 6.8.2a Mathematical functions
Function
Purpose
LEN(G$)
Returns the number of characters in G$.
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207
LEFT$(G$, N)
Returns the leftmost N characters of G$.
RIGHT$(G$, N)
Returns the right most N characters of G$.
MID$(G$, R, N)
ASC(G$)
Returns N characters starting at position R (from left)
in G$.
Returns the ASCII code for the first character of G$.
CHR$(N)
Returns the character with ASCII code N.
STR$(N)
Converts the value of N to a string:
B$ = STR(N).
VAL(G$)
Converts a string of digits (possibly with a decimal
point, a plus or minus sign, and an exponent) to a
numeric value: N = VAL(C$)
Table 6.8.2b String functions
The Figures given next shows how a mathematical and a string function
is used.
16
10 NUM = 256
20 ROOT_NUM = SQR(NUM)
30 PRINT ROOT_NUM
40 END
Figure 6.8.2a SQR function - program (left) & output (right)
10 D$ = “CONFIDENT”
20 E$ = LEFT$(D$, 3)
30 F$ = MID$(D$, 4, 4)
40 G$ = RIGHT$(D$, 2)
50 PRINT E$, F$, G$
60 END
CON
FIDE
NT
Figure 6.8.2b LEFT$, MID$ & RIGHT$ functions - program (left) &
output (right)
6.8.3 Arrays
An array is a sequence of a list of items arranged in a meaningful
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Programming
ordered pattern. It can be a list of class marks, height of students in a
class, temperature of each day in a month. The simplest form of an array
consists of items of data arranged in rows and columns. We assign a
variable name to an array just as we do for any other variables (numeric
or string). A simple form for assigning a value to an array is given
below.
10 Array_name (subscript)= value or string
Consider an array as table with one row and many columns. Now each
cell in this table will have a label (subscript) as shown below in Figure
6.8.3a.
Mark
15
25
30
12
1
50
Mark(0) Mark(1) Mark(2) Mark(3) Mark(4) Mark(5)
Figure 6.8.3a Array space in the memory
To enable us to identify each element of an array, we attach subscripts to
the array_name. These subscripts must be positive integers and enclosed
in parentheses. The minimum value we can use for a subscript is 0. Some
programmers prefer to start their subscript at 1. Each subscript of the
array acts as a separate variable with only the array_name related.
The array, Mark, has different values as subscripts. These values help
identify the different elements in the array Mark. Mark(0) to Mark(5)
are called array variables or sub scripted variables and the values are
called array values or elements of the array.
For example
10 PRINT Mark(5)
will instruct the computer to print the array value assigned to the array
variable Mark(5). The value displayed will be 50.
The DIM (Dimension) Statement
When dealing with array variables, we need to specify the maximum
number of elements an array can hold especially if it is to hold more than
10 elements. We do this by using the DIM statement. DIM is an
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209
abbreviation for DIMENSION meaning the magnitude or size. The DIM
statement instructs the program to reserve memory space for all the
elements specified in the array. This is called dimensioning. For arrays
with less than 10 elements, the DIM statement is not needed as the
program automatically caters for this. The form for dimensioning an
array is given below.
10 DIM Array_name(subscript)
The statement DIM Mark(20) instructs the program to reserve 21
memory locations for the elements of the array called Mark. The
computer identifies the elements of Mark as Mark(0), Mark(1), Mark(2),
… , Mark(20). The subscripts of an array cannot exceed the number in
the dimension i.e. the programmer has the choice of starting the array
with the subscript 0 (Mark(0)) and finishing it at Mark(20) – an array of
21 elements or he/she can start the array at Mark(1) and finish it at
Mark(20) – an array of 20 elements.
Using arrays with the FOR…NEXT statement
Arrays are best used when combined with the FOR…NEXT statement
otherwise they are basically the same as any other variable.
Figures given next shows how the FOR…NEXT statement is used to
create an array and how a DATA list is used to fill and prints the values
of an array.
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Programming
10 REM ARRAYS WITH FOR…NEXT & USER INPUT
20 DIM Height(14)
30 FOR I = 1 TO 14
40
INPUT Height(I)
50 NEXT I
60 REM PRINT OUT AN ARRAY
70 FOR N = 1 TO 14
80
PRINT Height(N)
90 NEXT N
100 END
Figure 6.8.3b For Loops to fill an array by user input and display its
elements
10 REM ARRAY FROM DATA LIST
20 DIM NUMBERS(12)
30 FOR I = 0 TO 12
40
READ NUMBERS(I)
50 NEXT I
60 FOR S = 0 TO 12
70
PRINT NUMBERS(S)
80 NEXT S
90 DATA 1,2,3,4,5,6,7,8,9,10,11,12,13
100 END
Figure 6.8.3c For Loops to fill an array from a DATA list and display its
elements
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211
Review Exercise 6.8.3
1. Determine the output for the following programs.
a.
10 REM ARRAY FROM DATA LIST
20 DIM W(14)
30 FOR I = 1 TO 12
40
READ W(I)
50
PRINT W(I)
60 NEXT I
70 DATA 2,4,6,8,10,12,14,16,18,20,22,24
80 END
b.
10 REM ARRAY FROM DATA LIST
20 DIM NUM(15)
30 FOR N = 0 TO 15
40
READ NUM(N)
50 NEXT I
60 PRINT NUM(6), NUM(10), NUM(13)
70 PRINT NUM(1) + NUM(12)
80 PRINT NUM(14)
90 REM PRINT NUM(N) IN REVERSE
100 FOR T = 15 TO 1 STEP –1
110 PRINT NUM(N);
120 NEXT N
130 DATA 2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32
140 END
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Programming
c.
10 REM CALCULATING MEAN
20 DIM NUM(12)
30 LET X = 0
40 FOR J = 1 TO 12
50
READ NUM(J)
60
PRINT NUM(J)
70
LET X = X + NUM(J)
80 NEXT J
90 PRINT
100 PRINT “The Mean is : ”; X/12
110 DATA 5,10,15,20,25,30,35,40,45,50,55,60
120 END
2. Write a program that allows the user to enter names of five of friends
into an array and displays them.
3. Modify the program in Question 2 to allow the user to enter the
name as well as the age and the best food and display them
accordingly.
6.9 Summary
1. Languages are used to facilitate communication with the computer
system.
2. Compiled language is a set of instructions to be compiled or
executed as a whole.
3. Interpreted languages allow instructions to be interpreted
individually or one line at a time.
4. Low level languages are closer to the 0s and 1s language of
computers.
5. High level languages are closer to the languages of humans.
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213
Key Terms
Coding
Debugging
Documentation
Logic error
Machine language
Procedural language
Sequence structure
Compiler
Desk checking
Interpreter
Loop structure
Problem oriented language
Selection structure
Syntax error
Review Questions – Multiple Choice
1. Which of the following QBASIC commands allows the programmer
to document or write comments in a program?
a. REM
b. CLS
c. DATA
d. PRINT
2. Which step below is not part of the program development process?
a. define the problem
b. design an algorithm
c. code the program
d. test the program language
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Programming
3. Which of the following types of error occurs as a result of wrong
input or misspellings?
a. input error
b. syntax error
c. content error
d. software error
4. The process of reading a QBasic program and reviewing its logic is
known as
a. Debugging.
b. Logic testing.
c. Desk checking.
d. Logical error testing.
5. The purpose of a compiler is to execute a set of
a. instructions as a whole.
b. instructions one line at a time.
c. QBASIC reserved words as a whole.
d. QBASIC reserved words one at a time.
Review Questions – Short Answers
1. Each of the program fragments given below has an error each.
Identify the error and write the corrected line only.
a.
b.
c.
d.
LET BONUS = 10%
READ NAME$, T1
LET SALES = 730
LET T = T1 * 2
e. PRINT BONUS * SALES
f. PRINT NAME, T
g. DATA RON, 6
2. Using an example briefly explain what run time error is?
3. Study the program below and answer the questions that follow.
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215
10 FOR L = 1 TO 50 STEP 2
20
LET SUM = SUM + L
30
LET NUM = NUM + 1
40
LET COUNT = COUNT + 1
50 NEXT L
60 LET AVG = SUM/COUNT
70 PRINT “AVERAGE = ”,AVG
80 END
a. Name the loop structure used in this program
b. List all the variables used in this program
c. Which QBASIC statement is used to store values within memory
cells?
d. What is the value of L when the loop is executed the third time?
e. What is the purpose of the program?
f. Which line number can be removed without affecting the correct
execution of the program?
4. Determine the output of the following code segment?
10 A$ = “This is a question”
20 B$ = “With no answer”
30 PRINT LEFT$(A$, 5) + MID$(B$, 6, 2) + RIGHT$(A$, 3)
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Programming
Additional Readings
Charles B. Kreitzberg and Norman T. Carpenter (Eds.)
(1984).Introduction To BASIC. Books for Professionals, Inc. ISBN 0-15600034-2
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition.
McGraw
Hill,
New
York,
2011.
Programming
217
Chapter 7
Data Communications and Networks
Internet: network of networks
After completing this chapter, you will be able to:
1. Describe the communications system
2. Describe data communication modes, types and transmission
factors
3. Describe the types of network
4. Describe network topologies and strategies
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Data Communications and Network
7.0 Introduction
Communication is the process of sharing data, programs and information
between two or more computers. An information systems (IS
effectiveness is measure in part by how efficiently it delivers information
and a data communication system is what enables an IS to carry out this
task. A data communication system also improves the flexibility of data
collection and transmission. For example, people these days use portable
and handheld devices, to communicate with the office at any time from
any location. All web based applications such as E-mail, Instant
messaging, Video conferencing, Internet telephone and E-commerce
depend on a good data communications system to effectively deliver its
services. By using the capabilities of data communication system,
organizations are no longer restricted by physical boundaries. They can
collaborate with other organizations, outsourcing certain functions to
reduces costs, and provide customer services.
7.1 Communication system
A communication system is made of four elements. Without these
elements working in tandem, communication via the internet would not
be possible. Whether wired or wireless, all communication systems must
have these four elements.
Figure 7.1a Communication system
Data Communications and Networks
219
Sending and receiving devices – are simply computers, mobile devices
such as PDA‟s, iPad, iPhone, tablets, mobile phones that transmit data to
each other.
Communication channels – is the actual medium through with data gets
transmitted from one device to another. This medium can be physical or
wireless.
Physical mediums: are actually wires/cables used to connect two or more
devices such as twisted pair, coaxial and fiber-optic cables. Twisted pair
cables are usually referred to as telephone lines and cat 5/6 cables. It is
called twisted pair because it consists of thin strands of intertwined
copper wires. Coaxial cable has a solid copper core in the middle which
is insulated thick rubber coating.
Coaxial cable has a solid copper core in the
middle which is insulated thick rubber
coating. Coaxial cables are usually used for
Twisted pair
transmitting television signals as well as
connect computers. It is approximately 80
times faster in transmitting data than a twister
pair. Fiber-optic cable is usually used a
Coaxial
backbone cable for extremely high speed data
transfer. It transmits data as pulses of light
through tiny tubes of glass. Since fiber-optic
cable uses pulses of light, it is capable of
Fiber-optic
transmitting data approximately 26,000 times
than the twisted pair.
Discovery Learning:
Figure 7.1b Physical
Medium
Find out if your mobile phone is Bluetooth/infrared capable. Try and
transfer some objects amongst your friends and observe the data
transfer rate.
Wireless mediums: are connections that do not use any physical
wires/cables, instead it uses radio frequency, microwave, satellite and
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Data Communications and Network
infrared to transmit data over the air. Radio frequency (RF) uses radio
signals to communicate between wireless devices. The radio frequency
standards are known as Bluetooth, Wi-Fi and WiMax. Bluetooth is a
short range RF communication that can transmit data in any direction
within ten metres. Wi-Fi (Wireless Fidelity) also uses RF to
communicate over short distances. It is based on certain standards and
each standard has a different transmission speed (11Mbps – 600Mbps).
WiMax (Worldwide Interoperability for Microwave Access) simple
extends the distance offered by Wi-Fi. Microwave uses high frequency
radio waves and requires line of sight access between the two
communicating devices similar to infrared. Microwave dish and satellites
act as relay station to transmit microwaves where line of sight is not
possible. Infrared uses infrared light waves to transmit data over very
short distances approximately thirty centimeters requires the
communicating devices to be in line of sight with no obstacles in
between.
Connection Devices – are devices that connect the devices to the
communication channels for data to be transmitted. For example, a
modem, network interface card (NIC) switch and routers are devices that
connect several computers and mobile devices together. Since the
computer understands digital language, everything that is sent and
received must be in 0‟s and 1‟s. The NIC, switch and routers send and
receive everything in 0‟s and 1‟s. However, if you are connected to the
internet from your home/office via a telephone line then a modem is
required for data transmission to take place.
Since the telephone lines were designed to
carry voice data i.e analog signals,
everything that leaves a computer system
must be converted into analog form.
Modems do just that, convert the digital
signal from the computer into analog signal
from the sending computer and converts the
analog signal back into digital signal on the
receiving computer. This process is known
Data Communications and Networks
221
as modulation-demodulation, hence the name modem (modulatordemodulator). While modems usually connect a single computer to the
internet, a switch and a router can connect hundreds to thousands of
computers in a network.
Analog – telephone signals; continuous electronic wave.
Digital – computer signals; presence or absence of an electronic pulse;
on/off
Figure 7.1c Connection
Device Signals
Discovery Learning:
Describe how a switch and a router work. Check the internet if your
computer lab does not have these devices.
Types of Modems
Telephone – can be either internal or external; connects computer
directly to a telephone line.
DSL (Digital Subscriber Line) – uses standard phone lines; external and
uses either USB or Ethernet ports.
Cable – uses coaxial cable – same as your television; uses either USB or
Ethernet ports.
Wireless – does not use cables and also known as WWAN (wireless wide
area network modem) (key term). Signals are sent through the air where
transfer speed or transfer rate (key term)-measured in bits per second
(key term); the higher the speed the faster the transfer rate.
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Data Communications and Network
Telephone
DSL
Cable
Wireless
Figure 7.1d Types of modems
Data transmission specifications – specify the rules and speeds at which
data is transmitted over the network. Protocols and bandwidth specify the
rules and speed respectively. Protocols are rules for exchanging data
between computers. The standard protocol for the internet is TCP/IP
(transmission control protocol/Internet protocol). TCP/IP is a two-layer
protocol. The higher layer, Transmission Control Protocol, manages the
assembling of a message or file into smaller packets that are transmitted
over the Internet and received by a TCP layer that reassembles the
packets into the original message. This process is known as
packetization.
Data Communications and Networks
223
The lower layer, Internet Protocol, handles the address part of each
packet so that it gets to the right destination. Each gateway
(router/server) on the network checks this address to see where to
forward the message. Even though some packets from the same message
are routed differently than others, they will be reassembled in
the original order at the destination. This process is known as
Discovery Learning:
Identify the sending/receiving devices, communication channels,
connection devices and data transmission specification used in your
school computer lab or office. Also find the IP address of your
computer
identification. TCP/IP uses domain name servers (DNS) that converts the
numeric based IP address into text based address (domain names – see
chapter 3 pg 3).
Bandwidth is the capacity of the communication channel that determines
the volume of data that can be transmitted in a given amount of time.
Figure 5 below shows the bandwidth for each channel type. Bandwidth is
measured in bits per second (bps).
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Data Communications and Network
Figure 7.1e Bandwidth Capacity
Discovery Learning:
Figure 5 does not show the capacity of fiber-optic cable. Find the
different categories of fiber-optic cables and their respective
bandwidth capacity.
Review Exercise 7.1
True/False
a) A communication system is made up of sending and receiving
devices only.
b) Data specification transmission is usually referred to as protocols.
c) Bandwidth is measured in bytes per second.
d) Wi-Fi stands for Wireless Fidelity.
Completion
a) _________ is a short range RF that can transmit data in any
direction.
d) The signals carried over the telephone lines are __________ signals.
e) A(n) __________ device that coverts digital signals to analog and
vice versa.
f) _____________ cables transmit data as pulses of light.
Short Answer Questions
a)
e)
f)
g)
What is the difference between Kbps, Mbps and Gbps?
Give at least two weaknesses of wireless communication systems.
Give an example of asynchronous transmission.
Describe the function of a modem.
Data Communications and Networks
225
7.2 Modes, types and transmission factors
Asynchronous and synchronous communication refers to methods by
which signals are transferred. These signals allow computers to transfer
data between components within the computer or between the computer
and an external network. Most actions and operations that take place in
computers are carefully controlled and occur at specific times and
intervals. Actions that are measured against a time reference, or a clock
signal, are referred to as synchronous actions. Actions that are prompted
as a response to another signal, typically not governed by a clock signal,
are referred to as asynchronous signals.
Asynchronous communication utilizes a transmitter, a receiver and a wire
without coordination about the timing of individual bits. There is no
coordination between the two end points on just how long the transmitter
leaves the signal at a certain level to represent a single digital bit. Each
device uses a clock to measure out the 'length' of a bit. The transmitting
device simply transmits. The receiving device has to look at the
incoming signal and figure out what it is receiving and coordinate and
retime its clock to match the incoming signal.
When the receiver of a signal carrying information has to derive how that
signal is organized without consulting the transmitting device, it is called
asynchronous communication. In short, the two ends do not always
negotiate or work out the connection parameters before communicating.
Asynchronous communication is more efficient when there is low loss
and low error rates over the transmission medium because data is not
retransmitted and no time is spent setting negotiating the connection
parameters at the beginning of transmission. Asynchronous systems just
transmit and let the far end station figure it out. Asynchronous is
sometimes called "best effort" transmission because one side simply
transmits, and the other does its best to receive and any lost data is
recovered by a higher level protocol. For example:
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Data Communications and Network
Asynchronous communication is used on RS-232 based serial devices
such as on an IBM-compatible computer's communication ports (COM
1, 2, 3 & 4) for the following functions:
o
o
PS2 ports on your computer use asynchronous serial
communication with the keyboard and mouse
The serial port is used to communicate with external devices such
as modems.
Asynchronous Transfer
communication.
Mode
(ATM)
also
uses
asynchronous
Asynchronous provides a faster means of connecting, but less reliable
when transmitting.
Synchronous systems negotiate the communication parameters at the
data link layer before communication begins. Basic synchronous systems
will synchronize the signal clocks on both sides before transmission
begins, reset their numeric counters and take other steps. More advanced
systems may negotiate things like error correction and compression.
It is possible to have both sides try to synchronize the connection at the
same time. Usually, there is a process to decide which end should be in
control. Both sides in synchronous communication can go through a
lengthy negotiation cycle where they exchange communications
parameters and status information. With a lengthy connection
establishment process, a synchronous system using an unreliable
physical connection will spend a great deal of time in negotiating, but not
in actual data transfer. Once a connection is established, the transmitter
sends out a signal, and the receiver sends back data regarding that
transmission, and what it received. This connection negotiation process
takes longer on low error-rate lines, but is highly efficient in systems
where the transmission medium itself (an electric wire, radio signal or
laser beam) is not particularly reliable.
Data Communications and Networks
227
All communications channel has a direction associated with it. Figure 6
shows the different directions of communication.
Discovery Learning:
A communication channel can never transmit data at its full
capacity. Determine the factors that affect the transmission for both
the physical and wireless mediums.
Figure 7.2a Channel Type
The message source is the transmitter, and the destination is the receiver.
A channel whose direction of transmission is unchanging is referred to as
a simplex channel. For example, a radio station is a simplex channel
because it always transmits the signal to its listeners and never allows
them to transmit back.
A half-duplex channel is a single physical channel in which the direction
may be reversed. Messages may flow in two directions, but never at the
same time, in a half-duplex system. In a radio telephone (RT) call, one
party speaks while the other listens. After a pause, the other party speaks
and the first party listens.
A full-duplex channel allows simultaneous message exchange in both
directions. It really consists of two simplex channels, a forward channel
and a reverse channel, linking the same points. The transmission rate of
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the reverse channel may be slower if it is used only for flow control of
the forward channel. Fiber-optic, twisted pair and all wireless
communication channels (page 3) are full duplex.
Review Exercise 7.2
True/False
a) In asynchronous communication, both the sending and receiving
devices must work on the same clock rate.
d) If you use a modem for your internet connection, the channel type is
full duplex.
e) Weather affects the transmission over the wireless medium.
Completion
a) In a __________ communication, a connection must be established
between the sending and receiving device before data transmission
can occur.
d) _________ duplex channel carries signals both ways but through
separate wires.
e) Asynchronous transmission is also known as _____________
transmission.
Short Answer Questions
a) List some factors that affect the transmission through physical
mediums?
d) How can the factors mentioned in (a) be minimized?
e) Give at least one advantage of asynchronous transmission over
synchronous transmission?
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229
7.3 Network Types
A network is formed when two or more devices are connected to each
other either to exchange data, share information and resources. A
network may consist of only microcomputers or a mixture of
microcomputers and mobile devices. There are five types of network:
LAN, WLAN, MAN, WAN and PAN. Each network type is
distinguished from each other by the geographical area it covers.
Local Area Network (LAN) – are networks that connect nodes which are
usually within the same room, offices, rooms within the same building
and even homes. LANs can be spread within a radius of one hundred
metres from the main building. LAN is typically owned or controlled by
a single organization.
Wireless LAN (WLAN) is a network that uses RF to connect computers
and other mobile devices. The data gets transmitted through a central
base station usually called the wireless access point. Wireless access
points converts the RF‟s into digital form (0‟s and 1‟s) and reroutes it to
its correct destination device.
Personal Area Network (PAN) is a wireless network formed
spontaneously with a very small area. It can be formed by devices like
your laptop, mobile phone and cordless mouse and keyboards which can
connect to each other spontaneously. This can also be regarded as an adhoc network which uses Bluetooth RF for data transmission.
Metropolitan Area Network (MAN) is a network that extends far beyond
the reach of a LAN. It usually connects offices that are spread around a
city or even across multiple cities within an approximate distance of one
hundred and fifty kilometers. MAN is typically owned by a group of
organizations who set/select the protocols and bandwidth in place for
data transmission to take place. Wide Area Network (WAN) is a network
that spans the entire globe such as the internet. All types of network must
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have all the elements of a communication system for it to be fully
efficient.
Discovery Learning:
Identify the type of network in your computer lab. What is shared
and how is it shared.
Review Exercise 7.3
True/False
a) PAN can also be regarded as LAN.
b) Internet is an example of WAN.
c) In a LAN environment a network gateway device can connect
several groups even if their configurations are different.
Completion
f) _________ connects several cities even regions.
g) A printer is a device that is usually shared in _________
environment.
Short Answer Questions
h) What is the difference between LAN and WLAN?
i) Give at least two advantages of setting up a network.
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231
7.4 Network Architecture
Network architecture describes how a network is arranged and how the
resources are coordinated and shared. It is divided in two major parts:
topology and strategy. Network topology describes how a network is
configured and arranged while strategies define how resources are
shared. There are six different topologies that exist today.
Bus network is where each device is connected to a common cable called
a bus or a backbone and all communication travel along this bus.
Figure 7.4a Bus Network
Ring network is where each device
is connected to two other devices,
forming a ring. Both the bus and
ring topology passes the message
from device to device till it reaches
its correct destination.
Figure 7.4b Ring Network
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Data Communications and Network
Star network is where each device
is connected a central device
usually a switch. When a node
sends a message, it first goes to the
switch which then verifies and
forwards the message to the correct
destination device. The star
network is the most widely used
network topology in the world.
Figure 7.4c Star Network
Tree network is also known as a
hierarchical network where each
device is connecting to another
device which may be connected to
other devices. It forms and upside
down tree where the root device is
usually the most powerful.
Hybrid network is a mixture of all
other
topologies.
Big
organizations have lots of smaller
networks based on differing Figure 7.4d Tree Network
topologies which are then
interconnected. For example, USP has twelve member countries and in
each campus there are several computer labs. Each of these labs are set
up using the star configuration which then is connected via a backbone
cable, microwave dish and satellite forming a tree and mesh network as
well.
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233
For Mesh network there is no
particular configuration; rather
the devices are connected to
each other on the fly especially
in the wireless domains. It is
best suited for WLANs and
PANs.
Figure 7.4e Hybrid Network
Figure 7.4f Mesh Network
Review Exercise 7.4
True/False
a) The architecture of the network describes its topology and strategy.
e) In a hierarchical network, a computer serving other computers can
also be hosted by other computer.
f) Messages are usually passed from one computer to another till it
reaches its destination in a star network.
g) Mesh network can be considered as a ad hoc network.
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Completion
h) A __________ is a device that usually forwards packets to the
correct computer in the star network.
i) Large organizations usually have a __________ network setup.
j) Network that is formed mostly by wireless devices on the move is
called ________ network.
Short Answer Questions
a) Describe how a PAN is formed?
b) Which topology is the most common and why?
c) What is the main reason some large organizations have to implement
a hybrid network?
d) Identify which network topology relates to which network type.
e) Draw the diagram of the topology used in your school computer lab
or office. Properly name the sending and receiving devices, channel,
connection devices and protocols used.
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235
7.5 Network Strategies
A network strategy describes how resources and information is
coordinated and shared. The most common network strategies are
terminal, client/server, peer-to-peer and distributed.
In a terminal server network, processing power is centralized in one
large computer (server), which can handle large number of connections.
All nodes connected to this server are either terminals with no or little
processing power or microcomputers running special terminal emulation
software such as Windows Remote Desktop. For example, most airline
reservation systems are terminal server networks. The server maintains
all airlines schedules including rates, seat availability, bookings and
flight arrival/departures. Travel agents use terminals to connect to the
server to make reservations. Although the tickets may be printed along
with travel itineraries at the agent‟s desk, nearly all processing is done by
the server. Another example is the Fiji tats lotto game; the terminals are
used only to supply
relevant data to the
server for processing.
Lotto tickets are usually
scanned for numbers
selected
and
these
numbers are sent to the
server for matching with
the drawn numbers. The
server processes all
tickets numbers and
processing the winning
tickets within a second.
Figure 7.5a Terminal Server model
Discovery Learning:
Describe how a point of sale (POS) system works in most supermarkets.
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Data Communications and Network
In a client/server network, the host computer usually the server
coordinates resources to other computers (clients) connected to it. The
software running on the client requests for information and services from
the server which then responds to individual clients. In a network, the
client/server model provides a convenient way to interconnect programs
that are distributed efficiently across different locations. Computer
transactions using the client/server model are very common. For
example, to check your bank account from your computer, a client
program in your computer forwards your request to a server program at
the bank. That program may in turn forward the request to its own client
program that sends a request to a database server at another bank
computer to retrieve your account balance. The balance is returned back
to the bank data client, which in turn serves it back to the client in your
personal computer, which displays the information for you.
The client/server model has become one of the central ideas of network
computing. Most business applications being written today use the
client/server model. So does the Internet's main program, TCP/IP. In the
usual client/server model, one server, sometimes called a daemon, is
activated and awaits client requests. Typically, multiple client programs
share the services of a common server program. Both client programs
and server programs are often part of a larger program or application.
Relative to the Internet, your Web browser is a client program that
requests services (the sending of Web pages or files) from a Web server
(which technically is called a Hypertext Transport Protocol or HTTP
server) in another computer somewhere on the Internet. Similarly, your
computer with TCP/IP installed allows you to make client requests for
files from File Transfer Protocol (FTP) servers in other computers on the
Internet. This model is most often used in middle to large organizations.
In larger organizations there may be several servers on the network, each
one dedicated to a particular service or task. For example, there could be:

An email server which provides a centralized email service for all
network users
Data Communications and Networks
237

File servers, to provide plenty of storage for different types of files.
It can be used to only store documents (wikipedia), a separate file
server can be used to store only videos (YouTube) etc
A print server which handles all of the print jobs required by network
users
An authentication server which handles all log-in and security
measures like windows server 2008 active directory
A web server



Figure 7.5b Client/Server model
Discovery Learning:
Select any organization and find out how the client/server model
works for this organization. You may draw a diagram like figure 14
to explain.
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Data Communications and Network
In a peer-to-peer network (P2P), nodes have equal processing
capabilities and can act as both the client and a server. s a type of
transient Internet network that allows a group of computer users with the
same networking program to connect with each other and directly access
files from one another's hard drives. Napster and Gnutella are examples
of this kind of peer-to-peer software. Major producers of content,
including record companies, have shown their concern about what they
consider illegal sharing of copyrighted content by suing some P2P users.
Meanwhile, corporations are looking at the advantages of using P2P as a
way for employees to share files without the expense involved in
maintaining a centralized server and as a way for businesses to exchange
information with each other directly.
How Does Internet P2P Work?
The user must first download and execute a peer-to-peer networking
program. (Gnutellanet is currently one of the most popular of these
decentralized P2P programs because it allows users to exchange all types
of files.) After launching the
program, the user enters the IP
address of another computer
belonging to the network.
(Typically, the Web page where
the user got the download will
list several IP addresses as places
to begin). Once the computer
finds another network member
on-line, it will connect to that
user's connection (who has
gotten their IP address from
another user's connection and so Figure 7.5c Peer-to-peer model
on). Users can choose how many member connections to seek at one
time and determine which files they wish to share or password protect.
Data Communications and Networks
239
Discovery Learning:
Select one example of a P2P model and describe how it works. You
may do your lab first to be able to fully understand how it works.
In distributed processing networks, processing capability is shared across
multiple nodes usually servers dispersed at different locations. This
strategy is common for very large organizations like banking industries.
For example, ANZ bank has it main server in Melbourne Australia, but
for Fiji customers, ANZ house has its own server that does the
processing for its Fiji customers. The account details are then replicated
to the main headquarters servers in Melbourne.
Note: you cannot have a network setup without either of the network
type, topology and strategy. If one is not implemented correctly, the
entire network will collapse. So when designing networks, you must first
describe the network type to be used, then the topology and finally the
strategy. In most cases, the topology in fact indirectly clarifies which
strategy and type is appropriate for a particular setup so choosing the
topology first helps.
Review Exercise 7.5
True/False
a)
b)
c)
d)
Star topology is the basis for a peer-to-peer model.
In a P2P model a computer can serve both as a client and server.
With distributed processing, everything processed at the main server.
A web browser is a sever program.
Completion
a) Windows _________ desktop is emulation software that enables
terminal networking.
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Data Communications and Network
b) ________ software enables computers to connect to each other
directly without a central server for exchanging files like music and
videos.
c) A ___________ server handles all the printing jobs in a large
organization.
d) In a(n) _____ processing network, computing power is located and
shared at different locations.
Short Answer Questions
e) What are the advantages and disadvantages of using a peer-to-peer
system?
f) Explain why the client/server model is most widely used?
g) What are the advantages of a distributed processing system?
Data Communications and Networks
241
7.6 Summary
1. Communication systems transfer data from one location to another.
It comprises of four elements:
 Sending and receiving devices
 Communication channels
 Connection devices
 Data transmission specifications (protocols)
2. Communication channels are either physical or wireless.
Physical channels: twisted pair, coaxial and fiber-optic cables.
Wireless channels: Radio frequency, microwave and infrared.
3. Connection devices connect the sending and receiving devices to the
communication channels. NIC, modem, switch and router are
commonly used connection devices.
4. Modems modulate and demodulate signals.
5. Major protocols in networking and internet are TCP/IP, FTP and
HTTP.
6. Bandwidth is the capacity of the communication channel.
7. Network topology describes how a network is configured.
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Data Communications and Network
8. Network strategy describes how the resources in the network are
shared.
Strategy
Terminal
Description
Centralized processing power, location and control;
underutilized processing power of microcomputers.
Client/server Clients request services; severs provide services and
coordination; efficient network management
software; expensive.
Peer-to-peer All nodes act as client and server; easy and
inexpensive; lacks security
Distributed Nodes share resources from different locations;
used in decentralized organizations.
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243
Key Terms
network
bandwidth
bits per second
network type
topology
strategy
router
twisted pair
tree
mesh
ring
WAP
node
terminal
client
server
channel
switch
NIC
coaxial
hybrid
microwave
P2P
workstation
GPS
WiFi
WiMax
Bluetooth
infrared
satellites
fiber-optic
radio frequency
star
bus
distributed
host
Review Questions – Multiple Choice
1) Which among the following is considered a line of sight
communication medium?
a. Broadcast radio
c. Bluetooth
b. Satellite communication
d. Infrared
2) ____ is the process of breaking down information sent or transmitted
across the Internet into small parts called packets.
a. Protocol
c. Identification
b. Bandwidth
d. Packetization
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Data Communications and Network
3) The essential features of this include identifying sending and
receiving devices, and packeting information for transmission across
the Internet.
a. Simple mail transfer protocol
b. Transmission control protocol/Internet protocol
c. File transfer protocol
d. hypertext transfer protocol
4) A network in which the central computer is a host to a cluster of
other computers that in turn are hosts is called a ____ network.
a. Star
c. Ring
b. Bus
d. Hierarchical
Review Questions – Short Answers
1) Describe how a GPS works.
2) Explain the process of modulation and demodulation.
3) Describe the differences between the three major physical
connection mediums: twisted-pair cable, coaxial cable, and fiberoptic cable.
4) What is a WLAN? How does it work?
5) Discuss the three types of RF: Bluetooth, WiFi and WiMax.
Research Question
6) Select an example (Google, Yahoo, Facebook, YouTube, Wikipedia)
from the internet or any other organization and describe how the
network type, topology and strategy are tied together.
Data Communications and Networks
245
Additional Readings
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition. McGraw Hill, New York, 2011.
Bidgoli, H. MIS2. Course Technology, Cengage Learning, Boston USA,
2010.
http://www.bookrags.com/research/asynchronous-and-synchronoustransm-csci-02/
http://www.inetdaemon.com/tutorials/basic_concepts/communication/as
ynchronous_vs_synchronous.shtml
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Chapter 8
Careers for Computing Professionals
The very framework of our society is being altered by
the fast-paced development of technology which reflects
how fast skills and requirements change career.
After completing this chapter, you will be able to:
1. Describe the various career paths available for computer
professionals.
2. To investigate the changing job structure as a result of the use of
computers.
3. To investigate the work of computer professionals.
Careers for Computing Professionals
247
8.0 Introduction
Due to changing technology, the information processing industry has
become one of the largest industries in the world with annual sales of well
over $100 billion. A job opportunity in the industry comes primarily from
three areas: The companies that provide the computer hardware; the
companies that develop computer software; and companies that hire
information processing professionals to work with these products. As in
any major industry, there are also many service companies that support
each of these three areas. An example would be a company that sells
computer supplies such as printer paper and optical discs.
8.1 Computer Industries and Careers
The Computer Equipment Industry
The computer equipment, or hardware, industry includes all manufactures
and distributors of computers and computer related equipment such as
computers, storage devices, terminals, printers and communication
equipment.
The Computer Software Industry
The computer software industry includes all the developers and distributers
of applications and system software. Thousands of companies provide a
wide range of software from operating systems to complete business
systems. The personal computer boom in the early 1980's provided
numerous opportunities in the software industry. Thousands of individuals
went into business for themselves by creating useful programs for the new
microcomputers. Many of these people started by working out of their
homes, developing their first software product in their own time while
holding other jobs.
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Information and Communications Technology (ICT)
ICT is often used as an extended synonym for information technology
(IT), but is usually a more general term that stresses the role of unified
communications and the integration of telecommunications (telephone
lines and wireless signals), computers, middleware as well as necessary
software, storage- and audio-visual systems, which enable users to
create, access, store, transmit, and manipulate information. The term ICT
is now also used to refer to the merging (convergence) of audio-visual
and telephone networks with computer networks through a single cabling
or link system. There are large economic incentives (huge cost savings
due to elimination of the telephone network) to merge the audio-visual,
building management and telephone network with the computer network
system using a single unified system of cabling, signal distribution and
management. This in turn has spurred the growth of organizations with
the term ICT in their names to indicate their specialization in the process
of merging the different network systems (Wikipedia).
Discovery Learning:
Give examples of ICT centers in Fiji and describe their roles
Information Processing Professionals
Information processing professionals are the people who put the equipment
and software to work to produce information for the end user. This
includes people such as programmers and system analysts who are hired by
companies to work in an information systems department.
What are the Career Opportunities in Information Processing?
The use of computers in so many aspects of life has created thousands of
new jobs. Some of these occupations, such as personal computer network
sales representatives, didn't even exist ten years ago. We describe some of
the current career opportunities, and encourage you to consider them as you
prepare for your future profession.
Careers for Computing Professionals
249
Working in an Information Systems Department
The various jobs within an information system department include: data
entry personnel, computer operators, computer programmer, system
analyst, database administrator, manager of information systems and etc.
The people in these positions work together as a team to meet the
information demands of their organizations. Another way to visualize the
positions and their relationship is to look at an organization chart.
Discovery Learning:
Draw an MIS Organization Chart.
In addition to management, the jobs in an information systems department
can be classified into five categories.
 Operations
 Data administration
 Systems analysis and design
 Programming
 Information centre
Operations personnel are responsible for carrying out tasks such as
operating the computer equipment that is located in the computer centre.
The primary responsibility of data administration is to maintain and control
an organization's database. In systems analysis and design, the various
information systems needed by an organization are created and maintained.
Programmers develop the programs needed for the information systems
and the information centre provides teaching and consulting services within
an organization to help users meet their departmental and individual
information processing needs. As you can see, an information systems
department provides career opportunities for people with a variety of skills
and talents.
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Careers for Computing Professionals
Sales representatives
Sales representatives must have a general understanding of computers and
a specific knowledge of the product they are selling. Strong interpersonal,
or people skills are important, including listening ability and strong oral and
written communications skills. Sales representatives are usually paid based
on the amount of product they sell, and top sales representatives are often
the most highly compensated employees in the computer company. Some
sales representatives work directly for equipment and software
manufacturers and others work for retailers. Most personal computer
products are sold through retailers who specialize in software only,
hardware only or both including service and repair.
Service and Repair
Being a service and repair technician is a challenging job for individuals
who like to troubleshoot problems and who have a strong background in
electronics. In the early days of computers, repairs were often made at the
site of the computer equipment. Today, however, malfunctioning
components such as circuit boards are usually replaced and taken back to
the service technician‟s office or sent to a special facility for repair. Many
equipment manufacturers are now including special diagnostic software
with their computer equipments that helps the service technician identify
the problem. Using a modem, some computer systems can automatically
telephone another computer at the service technician's office and leave a
message that a malfunction has been detected.
Consulting
After building experience in one or more areas of computing, some
individuals become consultants, people who draw upon their experience to
give advice to others. Consultants must have not only strong technical
skills in their area of expertise, but must also have the people skills to
effectively communicate their suggestions to their clients. Qualified
consultants are in high demand for such tasks as computer system selection,
system design and communications network design, and installation.
Careers for Computing Professionals
251
Education and Training
The increased sophistication and complexity of today's computer products
has opened wide opportunities in computer education and training.
Qualified instructors are needed in schools, colleges and universities and in
private industry as well. In fact, the high demand for teachers has created a
shortage at the university level, where many instructors have been lured
into private industry because of higher pay. This shortage probably will not
be filled in the near future; the supply of Ph.D.s, usually required at the
university level teaching, is not keeping up with the demand.
Discovery Learning:
In the information age explain how you would stay ahead of
technology.
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8.2 Preparing for a Career in ICT
To prepare for a career in the ICT industry, individuals must decide what
computer field they are interested in and obtain education in the field they
chose.
What Are the Fields in the Information Processing Industry?
There are actually three broad fields in the information processing industry:
Information Systems, Computer Science and Computer Engineering.
Information Systems (IS) refers to the use of computer systems to provide
the information needed to operate businesses and other organizations. The
field of Computer Science includes the technical aspects of computers such
as hardware operation and its efficiency and designing of application and
systems software. Computer Engineering deals with the design and
manufacturing of electronic components and computer hardware. Each
field provides unique career opportunities and has specialized requirements.
Obtaining Education for Information Processing Careers
The expanded use of computers in today's world has increased the demand
for properly trained computer professionals. Educational institutions have
responded to this demand by providing a variety of options for students to
study ICT. Trade schools, technical schools, community colleges, colleges
and universities offer formal education and certification or degree program
in ICT related fields. If you are evaluating a program offered by one of
these institutions, remember the three areas of information processing:
information systems, computer science and computer engineering.
Frequently, schools will have separate programs for each area.
Understanding the differences among the three fields will help you to find
the career you want. For example, in a university, courses relating to the
information systems may be listed with the business courses. Computer
science courses may be linked with mathematics and physics courses, and
computer engineering may be linked with electronic technology or
Careers for Computing Professionals
253
electrical engineering. Because schools list and organize their computer
courses in different ways, you should carefully read individual course
descriptions whenever you are selecting these courses.
With the wide variety of career opportunities that exist in ICT, it is difficult
to make anything other than broad general statements when it comes to
discussing degree requirement for employment in the industry. As in most
other industries the more advanced degree an individual has in a chosen
field, the better that individual's chances are for success.
Career Development in the ICT Industry
There are several ways for persons employed in the ICT industry to develop
their skills and increase their recognition among their peers. These include
professional organization or industry certifications like CISCO, MCSE,
CCNP, CCNA, MCSA, etc together with professional development and
continuing educational activities.
Professional Growth and Continuing Education
Because of the rapid changes in technology, staying aware of new products
and services in the ICT industry can be a challenging task. One way of
keeping up is by participating in professional growth and continuing
education activities. These broad categories includes events such as
workshops, seminars, conferences, conventions and trade shows that
provide both general and specific information on equipment, software,
services, and issues affecting the industry, such as computer security.
Workshops and seminars usually last a day or two, while conferences,
conventions and trade shows often last a week.
Another way of keeping informed about what is going on in the computer
industry is to regularly read one or more computer industry publications.
There is hundreds of publication to choose from. Some publication, such as
computer world and InfoWorld, are like newspapers and cover a wide range
of issues. Other publications are oriented towards a particular topic area
such as communications, personal computers, or a specific equipment
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Careers for Computing Professionals
manufacturer.
http://www.google.com/alerts?t=1&q=Latest+trends+in+ICT&hl=en site
allows you to register your email to receive latest updates in ICT in your
email account.
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255
8.3 Summary
Occupational
Categories
Task preformed
Computer Operators
Direct and monitor the operations of computer
systems by managing input, output, backup and
security
Service and Repair
Install equipment, perform routine maintenance
and repair faulty equipment
Programmers and
Analysts
Perform analysis and design new systems and
write programs
Sales and Marketing
Promote the sale of products, provide training
and field support
Design and
Engineering
Develop, design and produce computers
Web Master
Designs, creates, monitors, and evaluates web
sites.
Database
Administrator
Structures, coordinates, links, and maintains
databases.
Network Manager
Monitors existing networks and implements new
networks.
Technical Writer
Creates user manuals and documentation for
information systems.
Management and
Administration
Manage personnel, plan budgets and formulate
policies
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Key Terms
ICT
IT
Information Systems
Information processing
Computer Science
Computer Engineering
Review Questions - Research
Find five job advertisements in your local newspaper for computer
professionals. Find out what qualifications and educational requirements
are listed. What salaries and other benefits are stated? How many years
of experience are required? Do any sounds like jobs you would like to
have someday? Explain why or why not? Prepare a short report and
present it to the class.
Additional Readings
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition.
McGraw
Hill,
New
York,
2011.
Careers for Computing Professionals
257
Chapter 9
Desktop Publishing and Graphics
Desktop Publishing Software controls page
composition, typography, and the integration of
files created by other application software.
After completing this chapter, you will be able to:
1. Create simple publications.
2. Use formatting features available on MS Publisher.
3. Create PowerPoint presentations
4. Use formatting/animation features available in MS
PowerPoint.
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Desktop Publishing and Graphics
9.0 Introduction
Desktop Publishing (DTP) is a process of using a microcomputer, laser
printer, scanner and the necessary software to mix text and graphics and
create publications of professional quality. Some word processing
programs are being developed with these capabilities. However, we are
concerned with specialized software that allows you to create
publications that are of professional quality including graphics.
DTP software enables you to select a variety of typefaces just like
commercial printers use. It also allows you to select or create graphic
images – using scanners. The laser printer produces a high quality
printed result.
Discovery Learning:
What are some of the examples of DTP programs?
9. 1 Typesetting and DTP Features
Many publications mostly books and magazines for instance are created
by professionals trained in graphic arts and typesetting. They use
equipment that often cost several thousand of dollars.
Typesetting is concerned with deciding the size of spacing, location of
text and graphics and other details regarding typeface and graphics.
Typeface (or type style) describes the design and the sizes of a character
type.
Typography concerns the size, style and spacing of characters in a
document.
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File Integration combines different types of files together to produce
documents. This includes different files of interest such as clip arts,
scanned material, photographs and so on which are combined together
to make the document look more attractive and of better quality.
Page composition can enhance a document by using basic design
principals by having a landscape layout or portrait layout to catch
attention.
Kerning is using the shapes of the characters themselves to fit them
closer to each other.
However, there are many publications where such experience and
expenses are not necessary e.g. newsletters, forms, catalogues,
brochures, menus, advertisements and invitation/business cards. These
are all candidates of DTP.
Real estate agents may use DTP for sales sheets; travel agents may use it
for advertisements, architects for proposals, government officials for
presentation etc.
Features of DTP
Style sheets automate the selection of size and styles for headings and
captions as well as graphics. It enables you to make design decisions and
record them in a file. The same style can then be used over again. Their
use promotes consistency throughout a publication. They are sometimes
referred to as templates.
With a single mouse click, you can select the entire formatting and
design you need in a publication. Graphic images can be placed
anywhere on a page and text will automatically realign itself or overwrite
the image. Microsoft Publisher offers over 200 style sheets, which can be
modified and used for books, brochures newsletters etc. A user can even
create his/her own style sheet.
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Graphics - while text is important in page layout, it is usually the
graphics that catches the reader‟s eye. Thus, graphics are an important
element when designing a publication. The correct choice of graphics
will probably have more effect than the text that surrounds it.
Graphic images can be placed anywhere on a page and text will
automatically realign itself or overwrite the image. Graphics such as
photographs and drawings can perform various functions on a page. The
main reason for including graphics in publications is to
1) Attract the reader‟s attention and convey a message easily
2) Sometime graphics (such as a shaded box around a heading or in the
headline or in fallow corners) are used to attract the attention to the
start of a new story, concept, and the climax of the story or the
mood.
Clip-art is collection of graphics, images or text created by other
software which may be added to a document or design - pre-designed or
ready-made images. Clip-art is simply ready-to-go graphics. They are
kept in clip-art libraries. These clip-art libraries contain clip-art sets
(categories), which hold many clip-arts in relation to the category.
Fonts determine the typeface, size and style of printed characters.
Borders can be added around a page or to portions of text or to graphics
and images. This can be done to isolate ideas to draw attention to the
item.
Headings are strategically placed titles that intend to catch the eye of the
reader to the publication. It also indicates the start of a new story.
Columns can be created to fit entire blocks of text onto an area or the
entire page.
DTP lets you place various kinds of text and graphics together in a
publication design in almost any way you want. E.g. you are designing a
presentation for a new product. First you would type the text in a word
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processor. Then you would use other software to create graphics or you
might use graphics scanned from photographs of the product.
The DTP program allows you to integrate and look at your work on the
monitor on the same page i.e. you can import (copy) text and graphics
from different application programs, integrate them on the same
publication and view them together on the same page. You can also
make the necessary alterations you want (typesetting).
You can also look at two facing pages in reduced size of enlarged view
of a partial page. You can rearrange text in columns. You can enlarge or
reduce any columns and chose from all kinds of typestyles and sizes.
DTP programs also lets you decide how many columns of text can be
placed on a page.
You can place a graphic image anywhere in the page and text will
automatically re-align (wrap around) or flow over the image. You can
choose the setting yourself. Wrapping concerns the behavior of text
around a graphic image, auto shape or text box; text can wrap around,
square, behind or over the graphic.
Once a document is composed on the screen, it must be transmitted to an
output device that can print it out. DTP utilizes WYSIWYG. This task is
accomplished by what is known as a Page Description Language (PDL).
A PDL describes the size and positions of text and graphics to the
printer.
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9. 2 Summary
1. Desktop Publishing (DTP) is a process of using a microcomputer,
laser printer, scanner and the necessary software to mix text and
graphics and create publications of professional quality.
2. DTP uses style sheets that have predefined formatting features and
layout including graphics. The user only has to fill in the appropriate
texts.
Key Terms
Clip art
Style sheets
Graphics
Templates
Publications
Wrapping
Review Questions - Multiple Choice
1) Image editors use a special technique to smoothly blend two images
so that one image seems to melt into the next, often producing
amusing results. This technique is known as
a. Cropping.
b. Morphing.
c. Blurring.
d. Enveloping.
2) Various fonts, style sheets, clipart and graphics could be available
together in:
a. Dbase IV
b. Lotus 1-2-3
c. Educational software
d. Aldus Page Maker
3) In Desktop Publishing, which of the following will enable one to
determine the basic appearance of a single page or multiple pages?
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a.
b.
c.
d.
Style page
Master page
Page description language
Document description language
Review Questions - Completion
1) ________________ is a feature of a word processor or desktop
publishing package that shows on the monitor exactly how a
document will look like when printed.
2) _______________orientation is the horizontal layout of a page.
3) Controlling the final appearance of a document is referred to as
_______________.
4) A person who specializes in designing system software is known as
a(n) _________________.
5) A series of related jobs is called a(n) _______________.
Additional Readings
O‟Leary, T. J, O‟Leary, L. I. Computing Essentials 2012 Complete
Edition. McGraw Hill, New York, 2011.
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