A slot comprises the operating issue and data paths, a collection of one or more functional units (FUs) which share these resources. The term slot is common for this purpose in the VLIW world where the relationship between operation in an instruction and pipeline to execute is explicit. In dynamically scheduled machines, the concept is more commonly called an execute pipeline .
Modern conventional CPU -have compute Several pipelines (say two ALU , one FPU , one SSE / MMX , one branch ) Each of qui can issue one instruction per basic cycle purpose can-have Several in flight. These are what corresponds to slots. The pipelines may have several FUs – an adder and a multiplier , say – but only one in a particular cycle. The FU population of a pipeline / slot is a design option in a CPU.