Computer basic things to learn

8/13/2019 Computer basic things to learn

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FOUNDATIONS OF

COMPUTER SCIENCE

From Data Manipulation to Theory of

Computation


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Book

organization

Computersand Data

ComputerHardware

ComputerSoftware

DataOrganization

AdvancedTopics

Chapter 1: Introduction

Chapter 2: Data Representation

Chapter 3: NumberRepresentationChapter 4: Operations on Bits

Chapter 5: ComputerOrganizationChapter 6: Computer Network

Chapter 7: Operating Systems

Chapter 8: Algorithms

Chapter 9: ProgrammingLanguagesChapter 10: Software Engineering

Chapter 11: Data Structures

Chapter 12: Abstract Data Types

Chapter 13: File Structures

Chapter 14: DatabasesChapter 15: Data compression

Chapter 16: Security

Chapter 17: Theory ofComputation


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Introduction

Chapter 1


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1.1 THE COMPUTER AS A BLACK BOX

DATA PROCESSORYou can think of a computer as a data processor. Usingthis definition, a computer acts as a black box that accepts

input data, processes the data, and creates output data.

Although this model can define the functionality of a

computer today, it is too general.It is not clear how many types or sets of operations a

machine based on this model can perform.


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PROGRAMMABLE DATA PROCESSOR

This model adds one extra element to the computer: theprogram. A program is a set of instructions written in acomputer language that tells the computer what to do withdata.

In the new model, the output data depend on thecombination of two factors: the input data and the program.


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Same program, different input data


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Same input

data,

differentprograms


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1.2 VON NEUMANN MODEL

Every computer today is based on the von Neumann model.

It is based on three ideas.FOUR SUBSYSTEMS

The model defines a computer as four subsystems: memory,

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


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Memory

Memory is the storage area. It is where programs and data

are stored during processing.

Arithmetic Logic Unit (ALU)

The ALU is where calculation and logical operations take

place.

Control UnitThe control unit controls the operations of the memory,

ALU, and the input/output subsystem.

Input/Output

The input subsystem accepts input data and the programfrom outside the computer; the output subsystem sends

the result of processing to the outside.


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STORED PROGRAM CONCEPT

The von Neumann model states that the program must be

stored in memory. This is totally different from thearchitecture of early computers in which only the data were

stored in memory.

Both the data and programs should have the same format

because they are stored in memory. They are, in fact,stored as binary patterns (a sequence of 0s and 1s ) in

memory.

SEQUENTIAL EXECUTION OF INSTRUCTIONS

A program in the von Neumann model is made of a finitenumber of instructions. In this model, the control unit

fetches one instruction from memory, interprets it, and then

executes it.


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1.5 COMPUTER SOFTWARE

PROGRAMS MUST BE STORED

A SQUENCE OF INSTRUCTIONS

Another requirement of the model is that the program must

be a sequence of instructions. Each instruction operates on

one or more data items.


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ALGORITHMS

The step-by-step solution is called an algorithm.

LANGUAGESA computer language has a more limited number of symbolsand also a limited of words .

SOFTWARE ENGINEERING

Software engineering is the design and writing of structuredprograms. Today, it is not acceptable just to write a program

that does a task; the program must follow strict principles and

rules.

OPERATING SYSTEMSAn operating system originally worked as a manager to

facilitate access of the computer components for a program.

Today, operating systems do much more.


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1.6 HISTORY

MECHANICAL MACHINES (BEFORE 1930)

BIRTH OF ELECTRONIC COMPUTERS (1930-1950) Early Electronic Computers

The early computers of this period did not store theprogram in memory; all were programmed externally.

The first general-purpose, totally electronic computer wasmade by John Mauchly and J.Presper Eckert and wascalled ENIAC (Electronic Numerical Integrator andCalculator). It was completed in 1946.

Computers Based on the von Neumann ModelThe first computer based on von Neumanns idea wasmade in 1950 at the University of Pennsylvania and wascalled EDVAC (Electronic Discrete Variable AutomaticComputer).


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COMPUTER GENERATIONS (1950-PRESENT)

Computer built after 1950 are following, more or less, thevon Neumann model. The computers has become faster,

smaller, and cheaper, but the principle is almost the same.

Each generation witnesses some major change in

hardware or software (but not the model).

The first generation is characterized by the emergence of

commercial computers. Computers were bulky and used

vacuum tubes as electric switches.

First Generation (roughly 1950-1959)


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The invention of integrated circuit (transistors, wiring, and

other components on a single chip) reduced the cost and

size of computers even further. Minicomputers appeared

on the market. Software industry was born.

Third Generation (roughly 1965 -1975 )

Second-generation computers used transistorsinstead of

vacuum tubes. This reduced the size of computers as well astheir cost. Two high-level programming languages,

FORTRAN and COBOL , were invented and made

programming easier.

Second Generation (roughly 1959-1965)


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The fourth generation saw the appearance of

microcomputers. Advances in the electronics industryallowed whole computer subsystems to fit on a single

circuit board. This generation also saw the emergence of

computer networks.

Fourth Generation (approximately 1975-1985)

The fifth generation witnessed the appearance of laptop

and palmtop computers, improvements in secondary

storage media (CD-ROM, DVD, etc.), the use of

multimedia, and the phenomenon of virtual reality.

Fifth Generation (approximately 1985-NOW)


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