Overlapped Operation with Microprogramming

This paper presents a system for parallel operation of functional units in a processor that is under microprogram control. Specifically, for a multiple functional unit computer this new technique allows concurrent operation of the functional units without requiring hardwired instructions. A new interlock system for ordering execution of instructions is also presented. Two applications are shown: one to a three functional unit serial processor and one to an array processor. The mechanism allows holding instructions until the data on which they are to operate are ready and is a microcode version of that used on the IBM 360/91 or on the CDC 6600. This concurrency can be under either hardware, firmware, or software control.