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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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Understand the concept of a black box, a data processor, and Understand the concept of a black box, a data processor, and a programmable data processor.a programmable data processor.

Define the Define the von Neumannvon Neumann model and name its components: model and name its components: memory, arithmetic/logic unit, control unit, and input/output.memory, arithmetic/logic unit, control unit, and input/output.

Understand the stored program concept.Understand the stored program concept.

After reading this chapter, the reader should be able to:After reading this chapter, the reader should be able to:OOBJECTIVESBJECTIVES

Understand the sequential execution of statements in a program.Understand the sequential execution of statements in a program.

Name the components of a computer: hardware, software, Name the components of a computer: hardware, software, and data. and data.

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THE COMPUTERTHE COMPUTERAS A BLOCK BOXAS A BLOCK BOXTHE COMPUTERTHE COMPUTERAS A BLOCK BOXAS A BLOCK BOX

1.11.1

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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

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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von NEUMANNvon NEUMANNMODELMODEL

von NEUMANNvon NEUMANNMODELMODEL

1.21.2

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Figure 1-5

von Neumann model

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Figure 1-5

von Neumann model: Four subsystems

Memory Memory is the storage area

Arithmetic logic unit (ALU) The ALU is where calculation and logical operations

take place. Control unit

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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COMPUTERCOMPUTERHARDWAREHARDWARESee Chapter 5See Chapter 5

COMPUTERCOMPUTERHARDWAREHARDWARESee Chapter 5See Chapter 5

1.31.3

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DATADATADATADATA1.41.4

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Figure 1-5

Storing data 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.

Data

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COMPUTERCOMPUTERSOFTWARESOFTWARECOMPUTERCOMPUTERSOFTWARESOFTWARE

1.51.5

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Programs must be stored Programs are stored in

computer memory. (see Figure 1-6)

A sequence of instructions Programs must be a

sequence of instructions. (see Figure 1-7)

Why? Reusability.

Programming

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Figure 1-7

Program made of instructions

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Algorithms A step-by-step solution to a program is called an

algorithm. Languages

A computer language has a more limited number of symbols and also a limited number of words.

Software engineering The design and writing of programs in a

structured form. Operating systems

Computer Software

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HISTORYHISTORYHISTORYHISTORY1.61.6

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Computer generation First generation: vacuum tubs Second generation: transistors Third generation: integrated circuit Fourth generation: micro-computers Fifth generation: multimedia

History

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Key TermsAlgorithmArithmetic logic unit

(ALU)Black boxComputer languageComputer scienceControl unitData processorInput dataInstructionIntegrated circuit

MemoryMicrocomputerOperating systemOutput dataProgramProgrammable data

processorSoftwareSoftware engineeringVon Neumann model