| 摘要 |
PURPOSE:To make a decision on faulty qualities of a memory and memory driver circuit by forming address information as a memory output when access to an address space where no memory is packaged is attained in a diagnostic mode for the memory unit. CONSTITUTION:When memory driver circuit 1 commands a diagnosis by diagnostic command signal 11, attaining access to an address where no memory is packaged make address detection signal 13 of address detection circuit 4 change into [1] to instruct address selector circuit 3 to output address information, thereby outputting data to output 14. Therefore, access to address areas (a) and (c) with packaged memory is attained normally and the contents of memory 2 appear at output 14. In case of access to address area (b) with no packaged memory, address information is led out. Consequently, when different address information is outputted from output 14, a decision on the fault of circuit 1 is made to discriminate a fault memory element. |
