In an out-of-order processor, what is the difference between a reorder buffer and an instruction window?

Wikipedia says:
"In particular, in a conventional design, the instruction window consists of all instructions which are in the Reorder Buffer (ROB)."

Does this mean that the instruction window isn't a seperate hardware structure?


1 Answer 1


Correct. The instruction window is not a hardware structure. It is the set of instructions that is contained in the reorder buffer at any moment in time. Looked at another way: the reorder buffer is a container (like a drinking cup is a container) and the instruction window is the thing the reorder buffer contains (like milk, juice or water is the thing contained in a drinking cup.)


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