introduction ca

8/6/2019 Introduction CA

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INTRODUCTION

The word Computer means = to Calculate OR to

Evaluate .

People usually consider it as a calculating device which can

perform various arithmetic operations at very high speed . In this era more than 80% of the work done by computers is

non-mathematical or no-numerical nature.

More Accurately computer is an electronic device that

operates upon data.

What is Data ..?


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Data is organised information. It can be numbers,

words, measurements, observations or even just

descriptions of things

e.g. Marks obtained by students in various subjects

When used for preparing results.

Computer can store , process and retrieve data when

desired.so people perceives it as data processor.

The activity of processing data using a computer is

called data processing.


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Conclusion

Data is raw material which is used as input to data

processing.

Information is processed data obtained as output of

data processing.


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Characteristics Of Computers

Automatic -> Machine that works itself without

human intervention.

Speed -> Very fast device which performs lots ofoperation with in a few seconds.

Accuracy-> In addition to being very fast

,computers are very accurate . It Performs every

calculation with the same accuracy.

Diligence-> unlike human beings , a computer is

free from tiredness and lack of concentration.

cont..


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Versatility -> It is one of the most wonderful things

about a computer. It does multiple task at the same

time . Memory power-> It can retain a piece of

information as long as user desires.

No I.Q -> No intelligence of its own .Its I.Q is Zero

at least until today.

No Feeling -> Devoid of emotions. No feeling and

no instincts because they are machines.

Characteristics Of Computers


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Evolution Of Computers

Mark I computer in 1937-44 also know as

Automatic Sequence Controlled calculator.

ENIAC (1943-46) -> Electronic Numerical Integrator

And Calculator .

EDVAC(1946-52)-> Electronic Discrete Variable

Automatic Computer.

EDSAC (1947-49) Electronic Delay StorageAutomatic Calculator.

UNIVAC I(1951)-> Universal Automatic Computer.


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Computer Generations

FIRST GENERATION (1942-1955)

They used thousand of vaccum tubes . It is a fragile

glass device, which used filaments as a source ofelectronics which control and amplify electronic

signals.

Data and Instruction fed into the system from

punched card .

Instruction were written in machine and assembly

language.


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Characteristics Of Ist Gen.

Fastest calculating device of their time .

They were too bulky in size , require large rooms

for installation. They used thousand of vaccum tubes that emitted

large amount of heat and burnt out frequently.

They require constant maintenance.

Thousand of individual components were assembledmanually by hand into electronic circuit soproduction of these computer was difficult andcostly .


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Second Generation(1955-1964)

Walter Shockley invented a new electronic switchingdevice called transistor.

They were highly reliable as compared to tubes since

they had no parts like a filament that could burn out. They consumed almost one-tenth the power consumed

by a tube.

They were much smaller than a tube.

They were less expensive to produce. They dissipated much less heat as compared to vacuum

tubes.


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Characteristics Of 2nd Gen

They were more than ten times faster than the first

generation computers.

They were smaller than first-generation computerand required smaller space.

They consumed less power and dissipated less heat

than first-generation computers.

They were more reliable and less prone to

hardware failures than the first generation

computers.


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Third Generation(1964-1975)

They used Integrated chips(IC) which consist of

several electronic component like transistors ,

capacitors on a single silicon sheet called chip. Initially IC contained only 10-20 components called

small scale integration (SSI)

Later on hundred of components on a single chip

called medium scale integration (MSI) .


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Characteristics Of 3rd Gen.

They were more powerful than second generationcomputer . Because capable of performing1 million

instructions per sec. They were smaller than second-generation computer

requiring smaller space.

They had faster and larger primary and secondary

storage as compared to second-generationcomputers.

Time sharing o/s allowed simultaneous use of thesesystem by multiple users.


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Fourth Generation(1975-1989)

They were using microprocessor.

Semiconductor memories replaced magnetic core

memories resulting large random access with veryhigh speed.

Development of networking connections like LAN &

WAN.


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Characteristics Of 4th Gen.

PC were smaller and cheaper than mainframes or

minicomputers of third generation.

They consumed less power than third generationcomputers

They had faster and larger primary and secondary

storage as compared to third-generation computers. Graphical user interface (GUI) enabled for user to

quickly learn how to use computer.


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Fifth Generation(1989-Present)


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Computer Organization

Basic operations

Inputting Process of entering of data and instructions

into a computer system. Storing Saving data and Instruction to make them

readily available for initial or additional processing.

Processing- Perform arithmetic operations(+ , - , * , \)or logical operation(,==).

Outputting process of producing useful information orresult for a user ,such as printed report or visualdisplay.

ControllingDirecting the manner and sequence in

which the above operations are performed.


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Basic Organization Of Computer


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Input Unit

It accepts instructions and data from outside world.

It converts these instruction and data in computer

acceptable form. It supplies the converted instruction and data to

computer system for further processing.


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Output Unit

It accepts the results produced by a computer ,which

are in coded form and hence , we cannot easily

understand them. It converts these coded results to human acceptable

form.

It supplies the converted results to outside world.


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Storage Unit

Data and instruction required for processing

Intermediate results of processing.

Results for output ,before they are released to anoutput device.

Types :

Primary storageSecondary storage.


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Arithmetic Logic Unit

Is the place where actual execution of instructions

takes place during processing operation.

It takes data and Instructions from primary storage

for processing.

Types and no. of operations that a computer can

perform is determined by the ALU designer.


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Control Unit

When Input device know that it is time for it to feed

the data to storage unit..?

How does the ALU know what should be done withdata once they received?

How it is the only result for output are sent to an

output device ?solution-------> Control unit

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