User programme interrupt priority assignment in data processing - sub-systems have interrupt priority linked over user programme

摘要

A data processing system for use with multiplexed process control has a facility for interlocking the external priority interrupts with the user programme interrupt conditions. Three priority interrupt arrangements are internal to the processer. Two sub-systems are directly controlled by two designed user programs while a third is controlled by user program steps. External priority interrupts operate over a switching circuit and are combined with the internal assignments. Programme cycle control signals couple the three sub-systems together and enable the correct priority to be assigned to interrupt in the event of an error or command.