topic-piplelined instruction processing

8/2/2019 TOPIC-Piplelined Instruction Processing

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ByAditya pal

E1903-B56

1Prepared By - Aditya pal


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P i p e l i n eIt is the set of instructions by which we can

increase the output giving capability of anycomputer or any other digital electronicdevice.

Pipeline increases the execution process.

Pipeline refers to the fact that each step iscarrying data at once and each step isconnected to the next.

Prepared By - Aditya pal2


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It is the simple process we were using inour computers, as we gave instructions toour computers and they were beenexecuted.

Now in modern era instruction process issame but the feature is changed by the

new keyword PIPELINE.



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As the question arisesThe answer is simple in order to execute

out commands fast and easy we had tomake our instruction process simpler andfaster.

To make all the above easy and simplepipelining was introduced and is used nowdays by users.



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Pipelining is a new concept and was veryeffective to the world of computer

The origin of pipelining is thought to beeither the ILLIAC II project or the IBMStretch project. The IBM Stretch Projectproposed the terms, "Fetch, Decode, and

Execute" that became common usage.



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Instruction fetchFetch the instruction, retrieve operandsfrom registers Instruction decode and register fetchDecode the fetched instruction and also fetches the

registry ExecuteExecute arithmetic instruction, compute branch targetaddress, compute load/store ,Memory address

Memory access

Access memory for load or store, Fetch instruction at target ofbranch

Register write backWrite instruction results to registers



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When a programmer (or compiler) writesassembly code, they make the assumptionthat each instruction is executed before

execution of the subsequent instruction isbegun. This assumption is invalidated bypipelining. When this causes a program tobehave incorrectly, the situation is known as a

hazard. Various techniques for resolvinghazards such as forwarding and stalling exist.



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The cycle time of the processor is reduced,thus increasing instruction issue-rate inmost cases.

Some combinational circuits such asadders or multipliers can be made fasterby adding more circuitry. If pipelining is

used instead, it can save circuitry vs. amore complex combinational circuit.



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A non-pipelined processor executes only a singleinstruction at a time. This prevents branch delays (ineffect, every branch is delayed) and problems withserial instructions being executed concurrently.Consequently the design is simpler and cheaper tomanufacture.

The instruction latency in a non-pipelined processor isslightly lower than in a pipelined equivalent. This is dueto the fact that extra flip flops must be added to thedata path of a pipelined processor

A non-pipelined processor will have a stable instructionbandwidth. The performance of a pipelined processoris much harder to predict and may vary more widelybetween different programs



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topic-piplelined instruction processing

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