DATA PROCESSING SYSTEM

This data acquisition and control system includes many features for enhancing real time response to external or internal conditions. One feature relates to the use of multiple processor control circuits which can be switched between active and inactive status for controlling the performance of processor operations as a function of the level of priority of received interrupt service requests. Another feature pertains to I/O devices attached to the processor. These I/O devices include means for retaining data dynamically allocable by the processor program for specifying assigned interrupt levels and/or for identifying the requisite servicing subroutine in the processor to permit rapid response when an interrupt service is granted. The devices monitor their own status and provide a summary bit to the processor identifying whether or not a status data interchange is required. Multiple masking allows the processor to select between masking all interrupts, interrupts from any source on one or more interrupt priority levels, interrupts from a particular device or devices, or any combination of these.