introduction to computer science chapter 1

8/10/2019 INTRODUCTION TO COMPUTER SCIENCE CHAPTER 1

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Chapter 1

Introduction


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

a programmable data processor.

Define the von Neumannmodel and name its components:

memory, arithmetic/logic unit, control unit, and input/output.

Understand the stored program concept.

After reading this chapter, the reader should

be able to:

OBJECTIVES

Understand the sequential execution of statements in a program.

Name the components of a computer: hardware, software,

and data.


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Definition

A computeris a machinethatmanipulates dataaccording to a list of

instructions.

Computer Science defines as issuesrelated to the computer
http://en.wikipedia.org/wiki/Machinehttp://en.wikipedia.org/wiki/Data_(computing)http://en.wikipedia.org/wiki/Code_(computer_programming)http://en.wikipedia.org/wiki/Code_(computer_programming)http://en.wikipedia.org/wiki/Data_(computing)http://en.wikipedia.org/wiki/Machine


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1.1 THE COMPUTER AS A

BLOCK BOX

- Black box is a technical term for a

device or system or object

when it is viewed primarily in terms ofits input and output characteristics.

- Almost anything might occasionally

be referred to as a black box:

a transistor, an algorithm, humans, the

Internet.


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Figure 1-1

Data processor model

- A computer acts as a black box that

accepts input data, processes data and

creates output

- Problem : does not specify type of

processing / operations


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Figure 1-2

Programmable data processor model

-A program: is a set of instructions; what the

computer should do-Todays understanding : a set of instructions

written in a computer language

-Output data: consist of input 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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1.2 VON NEUMANNMODEL(VNM)


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VNM history

The von Neumann architectureis a

design model for a stored-program

digital computerthat uses a processingunitand a single separate storage

structure to hold both instructions and

data Its define how processing is done.

Based on three ideas
http://en.wikipedia.org/wiki/Digital_computerhttp://en.wikipedia.org/wiki/Central_processing_unithttp://en.wikipedia.org/wiki/Central_processing_unithttp://en.wikipedia.org/wiki/Computer_storagehttp://en.wikipedia.org/wiki/Data_(computing)http://en.wikipedia.org/wiki/Data_(computing)http://en.wikipedia.org/wiki/Computer_storagehttp://en.wikipedia.org/wiki/Central_processing_unithttp://en.wikipedia.org/wiki/Central_processing_unithttp://en.wikipedia.org/wiki/Digital_computer


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Figure 1-5

von Neumann model


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Idea 1:

Four Subsystems for VNM

Memoryis a storage area. Storeprograms & data during process

ALUcalculation & logical operations

take place Control Unitcontrols the operations of

the memory, ALU, IO subsystem IOinput; accepts input data/program

from outside computer,output; sends the result of

processing to the outside


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Idea 2: Stored Program

Concept

The program must stored in the memory

Stored in binary pattern : 1 or 0


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Idea 3: Sequential Execution of

instructions

Made of a finite number of

instructions

CU fetches one instruction frommemory, interprets it and execute


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1.3 COMPUTERHARDWARE


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Three broad categories

Central Processing Unit

Main Memory

Input/Output


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Storing data

Store in two state : presence or absence

Data such as text, image, audio, need to be

changed to appropriate form (0s and 1s)


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1.5 COMPUTERSOFTWARE


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Introduction

Computer software: a collection of

computer programs, proceduresand

documentation that perform some

tasks on a computer system

Programming: for these early

computers meant changing the wiring

systems or tuning on and off a set ofswitches.
http://en.wikipedia.org/wiki/Computer_programhttp://en.wikipedia.org/wiki/Procedureshttp://en.wikipedia.org/wiki/Procedureshttp://en.wikipedia.org/wiki/Computer_program


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Two aspect of programming to beunderstood.

In VNM, the programs are stored in

computer memory. Memory not onlyhold data, but also hold the program

(Figure 1.6)

i 1 6


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Figure 1-6

Program and data in memory

Programs Must Be Stored

Fi 1 7


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Figure 1-7

Program made of instructions;

Why? For Reusability

A Sequence Of Instructions


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Variety of Instructions

Algorithmstep-by-step solution

Languageto write computer

instruction Software engineeringthe design

and writing of structured programs

Operating systemswork as amanager to facilitate access of thecomputer components for a program


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1.6 HISTORY


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Mechanical Machines; Before

1930

Suanpan(the number

represented on this abacus

is 6,302,715,408) A mechanical calculator from

1914. Note the lever used to

rotate the gears.
http://en.wikipedia.org/wiki/Suanpanhttp://en.wikipedia.org/wiki/Suanpan


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1801: punched card technology

Punched card system of a music machine,

also referred to as Book music, a one-stop

European medium for organs

Punched cardwith

the extended

alphabet
http://en.wikipedia.org/wiki/Book_musichttp://en.wikipedia.org/wiki/Punched_cardhttp://en.wikipedia.org/wiki/Punched_cardhttp://en.wikipedia.org/wiki/Book_music


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Charles Babbage, 1823

The London Science Museum's

replicaDifference Engine, built from

Babbage's design.

Babbage is credited with inventing the first mechanical

computer that eventually led to more complex designs.

Part of Babbage's difference

engine, assembled after his death

by Babbage's son, using parts

found in his laboratory.
http://en.wikipedia.org/wiki/Science_Museum_(London)http://en.wikipedia.org/wiki/Replicahttp://en.wikipedia.org/wiki/Replicahttp://en.wikipedia.org/wiki/Science_Museum_(London)


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1930s1960s: desktop

calculators

The Curtacalculator can also

do multiplication and division
http://en.wikipedia.org/wiki/Curtahttp://en.wikipedia.org/wiki/Curta


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Advanced analog computers

Cambridge differential analyzer, 1938


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Early digital computers

Punched tapeprograms would be much

longer than the short fragment shown.Nine-track magnetic tape
http://en.wikipedia.org/wiki/Punched_tapehttp://en.wikipedia.org/wiki/Magnetic_tapehttp://en.wikipedia.org/wiki/Magnetic_tapehttp://en.wikipedia.org/wiki/Punched_tape


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Early Electronic Computers

Special Purposes computer ;The AtanasoffBerry

Computer(ABC) was the first electronicdigital

computingdevice.
http://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Computinghttp://en.wikipedia.org/wiki/Computinghttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Electronics


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Program-controlled computers,

general purposes machines

A reproduction of Zuse's Z1 computer.


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Colossus

Colossus was used to break German ciphers during World War II.
http://en.wikipedia.org/wiki/World_War_IIhttp://en.wikipedia.org/wiki/World_War_II


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COMPUTER GENERATIONS


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THIRD GENERATION

1965-1975 Use integrated circuit or microchip

Minicomputer appeared on the market


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Integrated circuit ofAtmelDiopsis 740

System on Chipshowing memory

blocks, logic and input/output pads

around the periphery

Microchips (EPROMmemory)with a transparent window,

showing the integrated circuit

inside
http://en.wikipedia.org/wiki/Atmelhttp://en.wikipedia.org/wiki/System_on_Chiphttp://en.wikipedia.org/wiki/EPROMhttp://en.wikipedia.org/wiki/EPROMhttp://en.wikipedia.org/wiki/System_on_Chiphttp://en.wikipedia.org/wiki/Atmel


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1969 Data General Nova.TV Typewriter
http://en.wikipedia.org/wiki/Data_General_Novahttp://en.wikipedia.org/wiki/Data_General_Nova


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FIFTH GENERATION

1985now Laptop & palmtop

The use of multimedia + VR

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