CONTROL SYSTEM OF PATROL ACTION

PURPOSE:To give a simultaneous patrol to all storage devices in the on-line mode, by installing a patrol request generating circuit also at the side of a processor to carry out the control for the storage device in the on-line mode. CONSTITUTION:Storage devices 1', 2', etc. are patrolled in the off-line mode by each of incorporated patrol request generating circuits 12, 22, etc. respectively, and the erasion of the stored contents is prevented even in the off-line mode. On the other hand, a patrol request generating circuit 32 is provided also at the side of a processor 3'. Thus the devces 1', 2', etc. select the circuit 32 via the selecting circuits 15 and 25 respectively to perform a patrol interruption. Therefore, a simultaneous patrol is possible for all storage devices in the on-line mode. As a fesult, the loss time due to the access time by the patrol can be reduced to increase the processing speed of information.