Two-stage pipelined execution unit and control stores

摘要

A two control store scheme with instruction execution overlay is shown in a data processing system execution unit having a two-state pipeline. The first control store controls the first-stage facilities during the first cycle of instruction execution and points to the initial location of the second control store. The second control store controls the second-state facilities during the final cycle of instruction execution. The second control store also controls the facilities of both stages during the intermeidate cycles of instruction requiring more than two cycles to execute. Because the second control store controls only the second-stage facilities during the final cycle, execution of the first cycle of the following instruction can take place concurrently within the first-stage facilities under the control of the first control store.