DATA PROCESSING SYSTEM FAULT DIAGNOSTIC ARRANGEMENTS DATA PROCESSING SYSTEM FAULT DIAGNOSTIC ARRANGEMENTS

摘要

The invention provides arrangements for diagnosing faulty equipment using background job diagnostic software running in the on-line PP250 system. Each processor is provided with a diagnostic interface which is connectable to a processor-store bus, either directly or by way of a multiplexor, and which is addressable as part of the PP250 memory complex. Each diagnostic interface provides facilities for (i) forcing data patterns into the microbits and the data area (highway HO), (ii) monitoring important points in the processor equipment such as highway HO, the data-out register, the microbits and (iii) various basic functions relative to the stopping of the micro-program. The diagnostic interface printed circuit boards are normally removed and inserted only when a processor is to be diagnostically exercised.