| 摘要 |
PROBLEM TO BE SOLVED: To allow the central processing unit to diagnose itself in a short time by generating the head address of a microinstruction for macroservice and performing interruption processing at an external self-diagnostic request, and conducting a self-diagnostic test according to a specific microinstruction for the self-diagnostic test. SOLUTION: A CPU 1 always monitors a signal requesting a self-diagnostic test sent from outside through a port by referring to a main memory 2 when macroservice is started. Once this request signal is detected, an entry of interruption processing is made to start the macroservice, and the head address of the microinstruction for the macroservice is generated to perform the interruption processing. Then a microprogram for self-diagnosis stored previously in a microprogram ROM 11 is read out and a self-diagnosis for an operation test, etc., of a mathematical arithmetic circuit 14 is conducted according to the microinstruction for the specific self-diagnosis, so that the diagnostic result is sent out through a specific port. |
