Device for setting aside memory for use by one transfer unit when number of busy responses for the unit regarding the memory becomes predetermined number

摘要

An input/output control device controlling data exchange between computers and memory units includes transfer units connected to the computers and accessing the memory units so as to effect the data exchange, an exclusive-control unit for preventing more than one of the transfer units from having access to the same one of the memory units by denying all but one of the transfer units the access, and an expropriation unit for taking control of one of the memory units when one of the transfer units is denied access to the one of the memory units a predetermined number of times, so that the one of the memory units can be set aside for use by the one of the transfer units.