JPS6410367A - Input and output control device - Google Patents

Abstract

PURPOSE:To prevent missing of common use control information at interruption of power supply by writing common control information into plural memories provided onto plural memories provided on the input/output controller applying common use control so as to multiplex the common use control information in writing the common use control information into the memories. CONSTITUTION:With a power supply for the 1st and 2nd input/output controllers turned on, an output signal 117 of a state setting circuit 63 set to output '1' from the 1st input/output controller and to output '0' from the input/output controllers, an output of a first-come discrimination circuit 11 having an output signal 117 of the state setting circuit 63 whose level is logical 1 is used for the both. In setting '1' to a first-come discrimination request register 60, an output 114 of a switching circuit 61 of the input/output controller receiving the signal earlier goes to '1', a value of a register 62 is outputted to an external connection bus 106 and the memory of the 1st and 2nd input/output controllers is accessed. That is, an address, a data and a control signal are transmitted/received to/from an external connection bus 106, and the data is read from the memory in the input/output controllers applying write/readout of the data to/from the memory 12 of 1st and 2nd input/output controllers to apply duplication of the common share memory.