IS 335: Information Technology in Business
Lecture Outline
Introduction to Computer Architecture
Objectives
• Discuss the development of automated computing
• Describe the general capabilities of a computer
• Describe computer system components and their functions
• List computer system classes and their distinguishing characteristics
• Define the roles, functions, and economics of application and system software
• Describe the components and functions of computer networks
(Computer) Systems Architecture
• Describes structure, interaction, and technology of computer system components
• Capabilities of a computer
– Accept numeric inputs
– Perform computational functions
– Communicate results
Automated Computation
• Mechanical
– Early computers with limited capabilities
– Performed repetitive mathematical calculations
• Electronic
– Electrons used rather than gears and wheels
– Fast, accurate reliable
Mechanical Implementation
• Mechanical representation of a mathematical calculation
• Difference engine: Charles Babbage, 1821
• Limitations and shortcomings
– Complex design and construction
• –Wear, breakdown, and maintenance of parts
– Limits on operating speed
Electronic Implementation
• Stores numerical values as magnetic charges or by positioning electrical switches
• Can convert physical movement into electrical signals, or vice versa
• World War II: impetus for change
• Faster and more reliable for complex calculations
• Easier to build than mechanical counterparts
Computer Capabilities
• General-purpose processor
• Storage capacity
• Flexible communication
Processor
• Device
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that performs data manipulation and transformation functions
Computation
Comparison
Data movement among memory, mass storage, and input/output devices
Processor (continued)
• Instructions
• Programs
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IS 335: Information Technology in Business
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Lecture Outline – Computer Architecture
General-purpose and special-purpose processors
Formulas and algorithms
Comparisons and branching
– Conditions
– Logic instructions
Storage Capacity
• Types of information to be stored
– Intermediate processing results
– Data
– Programs
• Characteristics of storage devices vary widely
– Cost
– Access speed
– Reliability
Input/Output Capability
• Must encompass many communication modes
– Sound, text, and graphics (for humans)
– Electronic or optical communication (for other computers)
Quick Quiz
1. A(n) _____ is a program in which different sets of instructions are applied to different data input
values
A. Formula
B. Algorithm
C. Processor
D. Condition
2. What are the typical devices within a computer systems? Why are there so many?
Computer Hardware
Hardware Components
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IS 335: Information Technology in Business
Lecture Outline – Computer Architecture
Central Processing Unit
• General-purpose processor
– Executes all instructions (computation and comparison functions)
– Directs all data movement
CPU Components
Arithm etic logic unit (ALU)
•
Contains electrical circuits that implement each
instruction
Registers
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Internal storage locations that can each hold a single
instruction or data item
Control unit
•
•
Controls movement of data to and from CPU
Accesses program instructions and issues appropriate
commands to ALU
System Bus
• Internal communication channel that connects all other hardware devices
• Main channel for moving data and instructions among hardware components
• Capacity is critical to performance, secondary storage, and I/O device performance
Primary Storage
• Also known as main memory
• Holds program instructions and data for currently executing programs
• Implemented with random access memory (RAM)
– Provides access speed and allows CPU to read or write to specific memory locations
– Volatile; does not provide permanent storage
Secondary Storage
• Composed of high-capacity nonvolatile storage devices that hold:
– Programs not currently being executed
– Data not needed by currently executing programs
– Data needed by currently executing programs that does not fit within available primary
storage
– Non-volatile; provides permanent storage
Comparison of Storage Types
Storage Type
Implementation
High-speed electrical
devices in the CPU
Primary storage
High-speed electrical
devices (RAM) outside
but close to the CPU
Low-speed magnetic
and optical devices
CPU registers
Secondary storage
Content
Currently executing instructions
and associated data inputs and
outputs
Currently running programs
and data needed immediately
(if they fit in primary storage
Programs not currently running
and data not currently being
accessed by programs
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Typical Quantity
Several dozen to a few
hundred instructions
and data items
1 to 8 billion data items
per CPU
Billions (Gigabytes),
trillions (Terabytes), or
quadrillions (Petabytes)
of data items
IS 335: Information Technology in Business
Lecture Outline – Computer Architecture
Input/Output Devices
• Implement external communication functions
• Human-oriented communication devices
– (e.g., keyboard, pointing devices, voice-recognition devices)
• Computer-oriented communication devices
– (e.g., modem, network interface unit)
Quick Quiz
1. The CPU contains a few internal storage locations called ______ .
2. True or False: Primary storage is also referred to as main memory.
Computer System Classes
M icrocom puter
•
•
Meets information processing needs of single user
Examples: PCs, network computers
P ortable
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Meets information processing needs of a single user at a
variety of levels
Examples: laptop, network, PDA
M idrange com puter
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Supports many programs and users simultaneously
M ainfram e
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Handles information processing needs of large number of
users and applications
Large amounts of data storage and access
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Designed for rapid mathematical computation
Supercom puter
Multicomputer Configurations
• Any organization of multiple computers to support a specific set of services or applications
• Common configurations
– Cluster
– Blade
– Grid
– Cloud
Cluster
• Group of similar or identical computers that cooperate to provide services or execute a common
application
– Connected by high-speed network
– Typically located close to one another
• Advantages: scalability and fault tolerance
• Disadvantages: complex configuration and administration
Blade
• Circuit board that contains most of a server
• Same advantages and disadvantages as a cluster, but also:
– Concentrate more computing power in less space
– Are simpler to modify
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IS 335: Information Technology in Business
Grid
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Lecture Outline – Computer Architecture
Group of dissimilar computer systems, connected by high-speed network, that cooperate to
provide services or execute a common application
Computers may be in separate rooms, buildings, or continents
Computers work cooperatively at some times, independently at others
Cloud
• Set of computing resources with two components:
– Front-end interfaces
– Back-end resources
• Specific way of organizing computing resources for maximum availability and accessibility
• Minimum complexity in the user or service interface
The Role of Software
• Translates user needs and requests into CPU instructions
• Performs complex translation process that bridges two gaps
– Human language to machine language (binary)
– High-level abstraction to low-level detail
Software Types
Application
program
•
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Stored set of instructions for responding to a specific request
Used directly by end users
Utility program
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Contains instructions for performing general-purpose tasks
Usually operates invisibly in the background
System softw are
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Performs utility functions needed by many application programs
Allocates computer resources to application programs.
Manages computer resources
Does not interact with end users
System Software Layers
• System management – utility programs used by end users and system administrators to manage
and control computer resources
• System services – utility programs used by system management and application programs to
perform common functions
• Resource allocation – utility programs that allocate hardware and other resources to multiple
users and programs
• Hardware interface – utility programs that control and interact with specific hardware devices
Operating Systems
• Most important and prevalent system software component
• Collection of utility programs that provides:
– Support for users and application programs
– Allocation of resources to multiple users and application programs
– Controlling access to hardware
Operating System Functions
• Program storage, loading, and execution
• File manipulation and access
• Secondary storage management
• Network and interactive user interfaces
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IS 335: Information Technology in Business
Lecture Outline – Computer Architecture
Application Development Software
• Programs used to develop other programs
• Types
– Program translators
– Program editors
– Debugging tools
– System development tools
Economics of System and Application Development Software
• System software consumes hardware resources
• Cost per unit of computing power has decreased rapidly
• Software is more cost effective when reused many times
Computer Networks
• Consist of hardware and software components that enable multiple users and computer systems
to share information, software, and hardware resources
• Enables many types of personal communication
External Resources
• Data available in many forms, including:
– Text files
– Sound and video
– Databases
• –Web pages
• One computer can ask another to run a program and transmit results or receive a file containing
a program and run it locally
• Can also share hardware devices of all types
Network Software
• Finds requested resources on the network
• Negotiates resource access with distant resource allocation software
• Receives and delivers resources to requesting user or program
• May also listen for and validate resource requests and deliver resources via the network
Network Communication and the Physical Network
• Network communication devices
– Simpler than I/O devices; do not need to convert data represented electronically into
another form
– Must support communication at high speeds
• Physical network
– Complex combination of communication protocols, methods of data transmission, and
network hardware devices
Summary
• Basic elements of computer system architecture
– Hardware
– Software
– Networks
• Computer system consist of a CPU, primary storage, secondary storage, and I/O devices
• Software translates user requests into machine instructions
• Operating system is most important system software component
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