An early failure detection system for a multiprocessor system has a plurality of central processing units. When an idling central processing unit is detected by a microprogram stored in a control memory or a control memory controller, a test program for testing the idling central processing unit is executed...http://www.google.de/patents/US4839895?utm_source=gb-gplus-sharePatent US4839895 - Early failure detection system for multiprocessor system
