Method of reducing wasted bus bandwidth in a computer system

Claim 1

In a computer system (10) having a plurality of master devices (masters) (M0, M1, M2, M(N)) that communicate with a plurality of slave devices (slaves) (S1, S2, S3, S(N)) over a shared bus (12), and wherein masters having operations to be conducted by slaves arbitrate to win bus control to permit a winning master to communicate with a selected one of the slaves, a method of reducing wasted bus bandwidth resulting from slow responding slaves comprising the steps of: a) issuing (24) from the winning master to the selected slave a request for service to be performed by the selected slave; b) signalling (BUSY - FIG. 2) the winning master from the selected slave, when the selected slave is either unavailable to service the request or unable to complete the requested service within a first predetermined time period, that the winning master should relinquish control of the bus; c) relinquishing (20, 44) control of the bus from the winning master in response to the signalling from step (b), the winning master becoming a relinquished master; d) arbitrating (36) for bus control at the selected slave, on the relinquished master's behalf, when the selected slave either becomes available to service the request issued in step (a) or has completed the requested service in step (a); and, e) detecting (42) at the relinquished master that the selected slave has arbitrated for bus control on the relinquished master's behalf, and, in response, arbitrating (22) for bus control at the relinquished master, the relinquished master, upon obtaining bus control, reissuing (24) to the selected slave the request previously issued in step (a); the bus thereby being available for communications between other masters and slaves during times that selected slaves are busy or cannot service requests within the first predetermined time period.