INPUT AND OUTPUT SYSTEM HAVING INTERSYSTEM COMMON- USE DEVICE

摘要

PURPOSE:To improve the precision of fault identification by allowing each input/output system which has an intersystem common-use device to judge by itself whether the device is reserved for the system or not when taking a diagnosis in case of fault occurrence. CONSTITUTION:A system 1A and a system 1B have a nuit control block (UCB) respectively and whether the input/output device belonging to each system is reserved or not is registered. When the input/output device of one system (2 for system A) is reserved by the system, diagnostic I/O is performed as it is and when not, a read reserved status common (RRS command) is chained with the head of the channel control word (CCW) of the diagnostic I/O to generate diagnostic I/O. The diagnostic I/O is completed according to the hardware reserved state of the intersystem common-use device 3.