| 摘要 |
PURPOSE:To prevent the generation of an operation disabled state by storing data to be written in a defective memory in a stand-by memory when the defective memory is detected at the time of executing the initial diagnosis of a microprogram memory. CONSTITUTION:This memory initial diagnostic circuit has a stand-by memory 21 in addition to microprogram memories 11 to 15 for normally storing microprograms, and when a defective memory is detected at the time of executing the memory diagnosis of these memories 11 to 15, 21, the information of the defective memory is stored in a defective memory information storing circuit 34, a write data selecting circuit 36 and a read data selecting circuit 37 are controlled by a defective memory data repairment control circuit 38 based upon the defective memory information and data to be written in the defective memory are stored in the stand-by memory 21 and driven. Thus even when a defective memory is generated, a central processing unit(CPU) 1 is not disabled and a program can be executed. |
