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Can any-one tell me what is the exact meaning of instruction dispatch and how Register based architecture avoid instruction dispatch ?

PsiX
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Saurabh Jain
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    The term "dispatch" can apply to an action in a processor pipeline (but this use does not seem to be the use for this question). Dispatch in this sense means either the sending of an instruction to a queue in preparation to be scheduled in an out-of-order processor (IBM's use; Intel calls this issue) or sending the instruction to the functional unit for execution (Intel's use; IBM calls this issue). E.g., see [this answer](http://stackoverflow.com/questions/8014739/what-exactly-is-a-dual-issue-processor#answer-8015472). –  May 08 '14 at 22:56

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Instruction dispatch involves fetching/reading an instruction from memory, and jumping to the corresponding segment of code that implements the instruction.

In a stack based architecture an addition would look like:

I1: LOAD C
I2: LOAD B
I3: ADD
I4: STORE A

You fetch the values from the stack and push the result back on it (hence the name stack based architecture).

In a register based architecture:

I1 "ADD, a, b, c"

a,b,c being registers.

A register based architecture does not completely avoid fetching instructions but it reduces the number of them.

PsiX
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