| 摘要 |
PURPOSE:To obtain a microcomputer having little possibility of pause of operation, by automatically operating a stand-by RAM in the place of a RAM to be connected at the initial stage of operation commencement as the main storage circuit of a CPU when the latter RAM is faulty. CONSTITUTION:A memory returning circuit is composed of an output port 101, gate circuits 102 and 103, and stand-by RAM6. When a faulty RAM is detected at the time of inspection of the writing and reading out operations of RAMs 1- 4, only output of the code of the faulty RAM is made and a chip enable signal to the faulty RAM is interrupted. Then the faulty RAM is electrically disconnected with a CPU and the enable signal is sent to the stand-by RAM6 so as to operate the RAM6 as part of the main storage circuit of the CPU istead of the faulty RAM. |
