Chapter 1 Introduction. Understand the concept of a black box, a data processor, and a programmable data processor. Define the von Neumann model and name.

Chapter 1

Introduction

Understand the concept of a Understand the concept of a black boxblack box, a , a data processordata processor, and , and a a programmable data processorprogrammable 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 Understand the stored programstored program concept. concept.

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

OOBJECTIVESBJECTIVES

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

Name the components of a computer: Name the components of a computer: hardwarehardware, , softwaresoftware, , and and datadata. .

THE COMPUTERTHE COMPUTERAS A AS A BLACK BOXBLACK BOXTHE COMPUTERTHE COMPUTERAS A AS A BLACK BOXBLACK BOX

1.11.1

Figure 1-1

Data processor model

• Data processor modelData processor model

Figure 1-2

Programmable data processor model

• Programmable Programmable Data processor modelData processor model

• ComputersComputers – general-purpose machines

ProgramProgram A program program

is a set of instructions that tells the computer what to do with data.

written in a computer language.

Figure 1-3

Same program, different data• Same program, different data

Figure 1-4

Same data, different programs

• Same data, different programs

von NEUMANNvon NEUMANNMODELMODEL

von NEUMANNvon NEUMANNMODELMODEL

1.21.2

von Neumann Modelvon Neumann Model Every computer today is based on

the von Neumann Model. It is based on 3 ideas:

1. Four subsystems

2. Stored Program Concept

3. Sequential Execution of Instructions

Figure 1-5

von Neumann model• Four subsystems:Four subsystems:1.1. MemoryMemory – the storage area of programs and data.

2.2. ALUALU – arithmetic/logic operations take place

3.3. Control UnitControl Unit – control Memory, ALU, and I/O

4.4. I/OI/O – accept input data/send output data

Input/Output SubsystemInput/Output Subsystem The definition is very broad;

it includes the secondary storagesecondary storage devices. DiskDisk – stores data and programs for processing

Stored Program ConceptStored Program ConceptThe von Neumann model states that

the program must be stored in memory.The memory of modern computers

hosts both a program its corresponding data

Sequential Execution of InstructionsSequential Execution of Instructions

A program is made of a finite number of instructions.

The control unit fetches one instruction from memory interpret it execute it

The instructions are executed one after another.

COMPUTERCOMPUTERHARDWAREHARDWARECOMPUTERCOMPUTERHARDWAREHARDWARE

1.31.3

ALU

Control unitRegisters

DATADATADATADATA

1.41.4

Storing DataStoring DataStore data in the form of an electrical

signal, specially its presence or absence.

This implies that a computer can store data in one of two states.

Binary number system

Data organizationData organizationAlthough data should be stored only in one

form (a binary pattern) inside a computer,data outside a computer can take many forms.

Data come in different forms: Numbers Text Images Audio Video

COMPUTERCOMPUTERSOFTWARESOFTWARECOMPUTERCOMPUTERSOFTWARESOFTWARE

1.51.5

Requirements of Requirements of von Neumann modelvon Neumann model

1. The programs must be stored in memory. (Fig. 1.6)

2. The programs must be a sequence of instructions. (Fig. 1.7)

Figure 1-6Program and data in memory

Fig. 1.6

Figure 1-7

Program made of instructions

Fig. 1.7 Program made of instructions

AlgorithmAlgorithm A programmer should

1. first solve the problem in a step-by-step manner and then

2. try to find the appropriate sequence of instructions that solves the problem.

The step-by-step solutionis called an algorithm

Operating SystemsOperating SystemsAn operating system originally worked as

a manager to facilitate access of the computer components for a program.

HISTORYHISTORYHISTORYHISTORY

1.61.6

Before 1950Before 1950Mechanical machines (before 1930)Early electronic computers (1930-1950)

ENIACENIAC (Electronic Numerical Integrator and Calculator)

first general-purpose, totally electronic computerUniversity of Pennsylvania, 19461946

19501950The preceding computers used

memory only for storing data.

EDVACthe first computer based on von Neumann’s idea,University of Pennsylvania,1950

Computer generationsComputer generations(1950-present)(1950-present)

1st generation (1950-1959)vacuum tubes

2nd generation (1959-1965)transistors, High-level languages(FORTRAN, COBOL)

3rd generation (1965-1975)IC(Integrated Circuit), Minicomputer, software industry was born

4th generation (1975-1985)VLSI, microcomputer

5th generation (1985-)laptop and palmtop computer

MicrocomputerMicrocomputerMicrocomputers are designed to be used

by individuals, whether in the form of PCs, workstations or notebook computers.

A microcomputer contains a CPU on a microchip (the microprocessor), a memory system (typically ROM and RAM), a bus system and I/O ports,

typically housed in a motherboard.