LOCK SIGNAL EXTENSION AND INTERRUPTION APPARATUS

An apparatus which receives locking signals from a first device and provides a lengthened version of certain of these signals to a second device. The apparatus stretches the locking signal provided to ensure that the signal remains valid throughout the entire locked sequence. The apparatus also indicates when arbitration windows are available between back-to-back locked cycles, i.e. when it is okay to relinquish control of the host bus to a requesting bus master or device. The apparatus monitors cache controller activity and notifies arbitration logic when the last write cycle of a read-modify-write sequence or multiple transfer write cycle begins. When the cycle completes, the arbitration logic releases the bus, thus providing an arbitration window for other requesting bus masters and devices. In this manner, overlock conditions which block bus masters from obtaining control of the bus are prevented from occurring.