DIAGNOSTIC SYSTEM FOR CACHE COINCIDENCE PROCESSING UNIT

PURPOSE:To attain the diagnosis of a cache coincidence processing unit with no use of a cache memory by providing a means to carry out a 1st diagnostic command that is written into a main storage only and a means to carry out a 2nd diagnostic command that sets a flag showing a diagnostic mode at '1' respectively. CONSTITUTION:An FFA 105 is set at '1' with a diagnostic command 2, and the data on an address (b) is rewritten with a diagnostic command 1. At the same time, the data on a main storage are rewritten with a cache memory kept as it is. Thereafter the FFA 105 is set at '0' although the output of an AND gate 107 is kept at '1'. Thus the output of the gate 107 is set at '0' and the address (b) is set at an FADR 101. Then the cache coincidence processing is carried out in the same way as usual, and the level '1' is invalidated.