Foundations of Computer Science
from Data Manipulation to Theory of
Computation
Behrouz A. Forouzan,
Brooks/Cole—Thomson Learning,
Pacific Grove, USA, 2003.
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Chapter 1
Introduction
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OBJECTIVES
After reading this chapter, the reader should be able to:
Understand the concept of a black box, a data processor, and
a programmable data processor.
Define the von Neumann model and name its components:
memory, arithmetic/logic unit, control unit, and input/output.
Understand the stored program concept.
Understand the sequential execution of statements in a program.
Name the components of a computer: hardware, software,
and data.
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1.1
THE COMPUTER
AS A BLOCK BOX
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Figure 1-1
Data processor model


You can think of a computer as a data processor.
Is it a specific-purpose machine or a general-purpose
machine?
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Figure 1-2
Programmable data processor model


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A program is a set of instructions that tells the computer what
to do with data.
A program is a set of instructions written in a computer
language.
The output data depend on the combination of two factors:
the input data and the program.
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Figure 1-3
Same program, different data
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Figure 1-4
Same data,
different
programs
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Figure 1-3
Same input data, same program

When the same program is run with the
same input, you expect the same output.
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1.2
von NEUMANN
MODEL
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Figure 1-5
von Neumann model
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Figure 1-5
von Neumann model: Four subsystems

Memory


Arithmetic logic unit (ALU)

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The ALU is where calculation and logical operations take
place.
Control unit


Memory is the storage area
The control unit controls the operations of the memory, ALU,
and the input/output subsystem.
Input/output


The input subsystem accepts input data and the program
from outside the computer.
The output subsystem sends the result of processing to the
outside.
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Figure 1-5
von Neumann model

Stored program concept:



The von Neumann model states that the program
must be stored in memory.
The memory of modern computers hosts both a
program and its corresponding data. They are
stored as binary patterns (a sequence of 0s and 1s)
in memory.
Sequential execution of instructions

A program is made of a finite number of
instructions. They are executed sequentially.
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1.3 COMPUTER
HARDWARE
See Chapter 5
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1.4
DATA
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Figure 1-5
Data

Storing data


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The von Neumann model does not define how data must be
stored in a computer.
A computer can store data in one of two states.
You will learn how to store different types of data as a
binary pattern, a sequence of 0s and 1s.
Organizing data (data organization)


Although data should be stored only in one form inside a
computer, data outside a computer can take many forms.
Data are organized into small units, small units are
organized into larger units, and so on.
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1.5 COMPUTER
SOFTWARE
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Programming

Programs must be stored


Programs are stored in
computer memory. (see
Figure 1-6)
A sequence of instructions

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Programs must be a
sequence of instructions.
(see Figure 1-7)
Why? Reusability.
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Figure 1-7
Program made of instructions
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Computer Software

Algorithms
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Languages
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A computer language has a more limited number of
symbols and also a limited number of words.
Software engineering


A step-by-step solution to a program is called an
algorithm.
The design and writing of programs in a structured
form.
Operating systems
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1.6
HISTORY
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History
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Computer generation
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First generation: vacuum tubs
Second generation: transistors
Third generation: integrated circuit
Fourth generation: micro-computers
Fifth generation: multimedia
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Key Terms
Algorithm
Memory
Arithmetic logic unit (ALU) Microcomputer
Black box
Operating system
Computer language
Output data
Computer science
Program
Control unit
Programmable data
processor
Data processor
Software
Input data
Software engineering
Instruction
Von Neumann model
Integrated circuit
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