Barner Robert Paul, Deveer John Anton, Oblonsky Jan Gustav: Memory control in a multipurpose system utilizing a broadcast. International Business Machines Corporation, November 6, 1973: US3771137 (146 worldwide citation)

In a multiprocessing computer where a plurality of processors, each with its own buffer memory, share a main memory, a broadcast system provides each processor the capability to query each other processor to determine whether a modified (e.g. updated) version of the desired data is located in anothe ...