Com611(ch-1)

Introduction to Computer 1

Computer Systems & Computer Systems &

Programming IProgramming I

Comp-611Comp-611

Department of Computer Studies Department of Computer Studies

UNIVERSITY OF YANGONUNIVERSITY OF YANGON


1.1 What is a computer?

3 points of view1. functional point of view

- information processing system capable of storing and manipulating numbers, words and pictures

2. organizational point of view- consists of hardware and software

3. user point of view- a teaching machine, a source of reference materials


To summarize the three points of view

- collection of hardware and software for

(a) data processing

(b) information processing

(c) knowledge processing


- The hardware is visible and tangible.

- The software is the soul of the machine.

- A computer without software is like a

car without gasoline, a camera without

film, a stereo without records.


Hardware

- physical part of the system

such as the system unit, video monitor,

printer, keyboard, mouse, scanner and other

peripheral devices.

Softwarethe name given to any kind of program which tells the hardware what to do.


1.2 History of Computing

The Abacus and Personal Computer

are two such devices separated by

thousands of years of history.


I. Early Calculating Devices - Abacus

- Napier's Bones

- Oughtrad's Slide Rule

- Pascal's Calculator

- Jacquard's Loom

- Babbage's Difference Engine

- Babbage's Analytical Engine

- Herman Hollerith-Punched Cards

5000 BC

to

1936 AD


II. Middle Computer

- Mark I Computer

- ABC

- ENIAC

- Stored Program Concept

- EDVAC

1937

to

1946


III. Modern Age Computers

- 1st Generation Computer

- 2nd Generation Computer

- 3rd Generation Computer

- 4th Generation Computer

- 5th Generation Computer

1948

to

Date


(1) Early Calculating Devices The Abacus (5000 BC)

• used for counting and computations

• consists of a frame with some bars fixed across it

• had some beads which could be moved along

each bar

• represented a position in the number system


Napier’s Bones

• John Napier, a Scottish Mathematician invented a tool which helped him in doing the tedious calculations involved in Astronomy.

• used 10 strips of bones called Napier’s Bones and divided each into 9 squares.

• each square was divided into 2 parts.

• The lower half indicated units and the upper half indicated tens.


Oughtrad's Slide Rule

• Napier also developed the method of

logarithm

• multiplication and division can be done

by adding and subtracting


Pascal’s Calculator (1642)

• great French Mathematician and Philosopher Blaise Pascal devised a calculating machine.

• consists of gears, wheels and dials.

• had 10 segments like that of house energy meters.

• When one wheel completed a rotation,the next wheel moved by one segment.


Jacquard’s Loom (1801)

• A French weaver, Joseph Jacquard used punched cards (Jacquard’s Loom) to determine the threads to be selected in weaving patterns automatically.

• A hole in the card permitted a hooked wire containing a thread.


Babbage’s Difference Engine and the Analytical Engine

• supposed to be a general purpose computer that

could add, subtract, multiply, and divide in

automatic sequence at a rate of 60 additions per

second.

• design would cover the area of a football field

and be powered by a locomotive engine.

• used punched cards to enter data


Herman Hollerith’s Tabulating Machine (1890)

• Dr Herman Hollerith, the next contributor to

development of computer.

• used punched cards to store and tabulate census

information.

• could sense the punched holes, regonise the

number, and make the required calculations.


(2) Middle Age Computers

• In 1937, Harvard professor Howard Aiken set out to build an automatic calculating machine to combine electrical and mechanical technology with Hollerith's punched card techniques.

• In 1944, was completed.

• Internal operations were controlled automatically with electromagnetic relays, arithmetic counters were mechanical computer.

IBM Mark I


ABC (Atanassoff-Berry-Computer)

• During 1937-1938, John Vincent Atanassoff began to build the first electronic computer.

• call it ABC.

• used vacuum tubes for storage and arithmetic logic functions.

• designed for the special purpose of simultaneous equations.


ENIAC (Electronic Numerical Integrator And Calculator)

• In 1940 and 1941, Mauchly teamed up with J. Presparo Eckert, Jr.

• ENIAC was the first electronic general-purpose computer to be put into full operation

• vacuum tubes were used in ENIAC.


Stored Program Concept

• In the mid 1940, H.Goldshine, A.W Burks and

John Von Newmann wrote a paper suggesting.

– Binary numbering systems can be used

– Computer instructions as well as the data being

manipulated could be stored internally in the machine.


EDVAC

• Mauchly, Eckert and others at the Moore

school set out to build a machine with stored

program capability

• called EDVAC

• carries the distinction of being the first

stored program electronic computer


(3) Modern Age Computers

• used vacuum tubes

• fragile, overheating and frequent breakdowns

• machine language were used

e.g. ENIAC

First Generation Computers


Second Generation Computers

• used transistors instead of tubes

• smaller, faster and more reliable and

produced far less heat

• much smaller device based on

semiconductor.

e.g. IBM 1401, LEO III, UNIVAC and

ANLAS


Third Generation Computers

• development of integrated circuit (IC)

technology in the mid-1960

• DRAM were used for primary storage.

e.g. ICL 1900 series, IBM 360 series


Fourth Generation Computers

• large scale integration (LSI) of circuits

• more powerful, reliable and compact computer

e.g. Silo Z80, Inter 8086, 8088, 80286, ....


Fifth Generation Computers

• based on artificial intelligence

• parallel processing and superconductors is

helping to make artificial intelligence a reality

• goal is to develop devices that respond to natural

language input and are capable of learning and

self-organization.


classified by• CPU sizes• number of on line terminals• maximum disk storage capacity and• all other available I/O devices

categories:1. Microcomputers2. Minicomputers3. Mainframes4. Supercomputers

1.3 Classification of Computers


(1) Microcomputers

• personal computers

• contains a microprocessor

• designed for individual personal use

• non-portable and portable computers

• Portable computers- laptop, notebook, sub

notebook and pen based


(2) Minicomputers

• task-oriented computers

• more powerful than microcomputers

• many operators can use a minicomputer

simultaneously

• most powerful minicomputers are called super

minicomputers


(3) Mainframe Computers

• large computer systems

• can handle hundreds of users

• store large amount of data

• process transactions at a high speed


(4) Supercomputers

• largest, most expensive real-time computer

systems

• carry out 50 to 100 million instructions per second


1.4 Structure of a Digital Computer

Block Diagram of a Digital Computer

CPU

ALU CU

IMMEDIATE ACCESS STORE

INPUT DEVICE

OUTPUT DEVICE

BACKING STORAGE


a) Input Devices

• read the necessary data into the machine

• cannot understands

• to translate all data into electronic pulses

• keyboards, mouse, scanner, punched-card, magnetic

tape readers etc.


b) Central Processing Unit

• main part of a computer

• all processing is carried out

• controls the activities of the whole computer

configuration

1. Arithmetic and Logic Unit

2. Control Unit

3. Memory


Functions of a CPU -

1. to store data as well as instructions

2. to control the sequence of operations

3. to issue commands to all parts of computer

system

4. to carry out data processing and to send

results to output


1. Arithmetic and Logic Unit (ALU)

• operates on the data available in the main memory and

send them back after processing, once again to memory.

Functions of the ALU -

1. to carry out arithmetic operations like additions,

subtraction, multiplication and division.

2. to performs certain logical actions based on AND and

OR functions.


2. Control Unit

• directs all operations inside the computer

• heart of the computer because it controls and

coordinates all hardware operations

i.e. hose of the CPU and input output devices


Main functions -

1. to transfer data from the input device to the

memory to the Arithmetic logic unit

2. to transfer the results from memory to the output

device for printing

3. to stores the program in the memory, takes

instructions one by one, understands them and

issues appropriate commands to the other units


3. Memory• computer's main memory or primary memory

• able to store information, which can be recalled or

accessed when required

• Main high speed memory is limited in size and very

costly to buy; as such, only limited memory is provided.

• Rest of the programs and data are kept in secondary

storage devices also known as backing storage devices.


Main functions -

1. Instructions waiting to be obeyed by other components

of the CPU.

2. Instructions currently being obeyed.

3. Data awaiting processing.

4. Data currently being processed.

5. Processed data awaiting output.


c) Output Devices

• Results of any computer processing has to be

communicated to the user.

• translate the computer output into a form

• CRT displays, printers, card-readers etc.


Unit Function

Input Reads information from input device and feeds to the computer in coded form.

Storage Unit Stores program instructions and data.

Arithmetic & Logic Unit

Performs arithmetic and logic operations.

Control Unit Interprets program instructions and initiates control operations.

Output Unit Decodes information and presents it to the user.

The five basic units of a computer


5. Software

• a set of instructions written in various

computer languages

Two main types

(1) System software

(2) Application software


(1) System Software

• consists of programs that are used to control

and operate the computer hardware.

• three components: the operating system,

utility programs and language processors.


• The operating system

• how to perform functions such as how to

load, store and execute programs

• how to manage resources available (CPU

time).

• Utility program

• are not available in application software,

such as formatting a diskette and creating a

directory.


(2) Application Software

• consists of programs created to perform a

specific user's task.

• allows a user to prepare a document, design a

financial worksheet or create a useful database.

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