Test by Bikram | Computer Organization and Architecture | Test 2 | Question: 3

Question

A processor is having an instruction which can move a string of Bytes from one memory location to another. The fetching and decoding of the instruction takes $10$ clock cycles.

To transfer each Byte instruction takes $20$ clock cycles. The processor is clocked at a rate of $10$ Ghz. If the instruction can transfer a string of $64$ Bytes then to execute the instruction,  time required is ________ns

Answer 1

fetch and decode operations takes 10 clock cycles

One Byte transfer takes 20 clock cycles

then 64 Bytes takes = 20 * 64 = 1280  clock cycles

Total execution time = 10 + 1280 =  1290 clock cycles 

so time require for execution of the instruction is : (1290/10Ghz) sec = (1290 /10 ) * 10^-9  sec = 129 nsec 

Comments

@bikram sir

my doubt is to calculate to execution time

will we consider the fetch and decode time?

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@hem chandra Joshi

yes, here we need to consider the fetch and decode time while calculating total execution time .

as after fetching and decoding , the instructions only get executed .

So total execution time = Instruction fetch & decode time + Instruction execution time