Basic Organization of a Computer

8/3/2019 Basic Organization of a Computer

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Basic Organization of a Computer


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FIVE BASIC OPERATIONS

Inputting. The process of entering data andinstructions into the computer system.

Storing. Saving data and instructions so that

they are available for initial or for additionalprocessing.

Processing. Performing arithmetic operations

or logical operations on data in order toconvert them into useful information.

Outputting. The process of producing usefulinformation or results for the user.

Controlling. Directing the manner andsequence in which all of the above operationsare performed.


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The Internal Architectural Designof Computers Differs From OneSystem Model to Another.However, the Basic OrganizationRemains the Same for All

Computer Systems.


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BASIC ARCHITECTURE


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Input Un it

Data and instructions must enterthe computer system before anycomputation can be performed onthe supplied data. This task isperformed by the input unit that

links the external environmentwith the computer system.


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The following functions areperformed by an input unit:

It accepts (or reads) the list ofinstructions and data from the outside

world. It converts these instructions and data

in computer acceptable form.

It supplies the converted instructionsand data to the computer system forfurther processing.


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Out put Un it

The job of an output unit is just

the reverse of that of an inputunit. It supplies information andresults of computation to theoutside world.


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The Following Functions Are Performed byan Output Unit: -

It accepts the results produced by thecomputer, which are in coded form andhence cannot be easily understood byus.

It converts these coded results tohuman acceptable (readable) form.

It supplies the converted results to theoutside world.


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St orage Uni tThe data and instructions that are

entered into the computer systemthrough input units have to be storedinside the computer before the actual

processing starts. Similarly, the resultsproduced by the computer afterprocessing must also be keptsomewhere inside the computersystem before being passed on to theoutput units.


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The Specific Functions of the Storage UnitAre to Hold (Store): -

All the data to be processed and theinstructions required for processing(received from input devices).

Intermediate results of processing. Final results of processing before these

results are released to an output

device.


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Ari t hm et i c Log ic Un it

The arithmetic logic unit (ALU) of acomputer system is the place

where the actual execution of theinstructions takes place during theprocessing operation. To be more

precise, all calculations areperformed and all comparisons

(decisions) are made in the ALU


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The type and number of arithmetic andlogical operations that a computer can

perform is determined by theengineering design of the ALU.

However, almost ALU'S are designed toperform the four basic arithmetic, add,subtract, multiply, divide and logic

operations or comparisons such as lessthan, equal to or greater than


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Cont ro l Uni t How does the input device know that it

is time for it to feed data into thestorage unit?

How does the ALU know what should

be done with the data once they arereceived?

And how is it that only the final resultsare sent to the output device and notthe intermediate results?


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The control unit acts as a centralnervous system for the other

components of the computer. It manages and coordinates the entire

computer system.

It obtains instructions from theprogram stored in main memory,

interprets the instructions, and issuessignals that cause other units of thesystem to execute them.


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Cent ra l Proc ess ing Uni t

The control unit, the arithmeticlogic unit and primary storage of acomputer system are jointlyknown as the Cent ra l Pr ocessin g Un i t (CPU).

The CPU is the brain of anycomputer system.


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The Syst em Conc ept

A system is a group of integrated partsthat have the common purpose ofachieving some objective(s).

A system has more than one element. All the elements of a system are

logically related.

All the elements of a system arecontrolled in such a way that thesystem goal is achieved.

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Basic Organization of a Computer