BUS ACCESS CONTROL METHOD

摘要

PURPOSE: To attain the effect distribution of bus access by counting continuous bus request signals. CONSTITUTION: Control of access to a bus by a node necessitates plural sets of access control counters and registers, one set includes three different counters and registers and one set is assigned to every priority order level on each bus. A downstream access request(DAR) counter 56 being one of the counters in each set counts the number of downstream nodes which request access to the bus. The downstream nodes of a node 38 on a bus 46 can request access by including request bits in a call transmitted to the node 38 on a bus 48. The DAR counter 56 counts the number of continuous bus request bits in each priority order level in the cell while being transmitted by the bus 48 and a string request counter 59 transfers the request bits to the next node. Thus, access can be efficiently distributed.