| 摘要 |
PURPOSE:To realize the monitor even to such a fault with which the output of a temporary memory is fixed without increasing the memory capacity, by using a monitor time slot before a write mode to read and write a test signal. CONSTITUTION:In a memory monitor mode the main signal which exchanges a time slot is first connected to a test signal produced by a test signal producing circuit 6 through the 1st selection circuit 23. This test signal is written to a temporary memory RAM1. That is, the test signal is written to an address position formed by a test address counter 8 by the position a monitor time slot before a write mode. The written test signal is read out in the next timing. A pattern collation circuit 7 monitors whether the correct reading/writing is carried out. In such a way, the monitor is possible even to such a fault with which the output of a temporary memory is fixed without increasing the memory capacity by using a monitor time slot before a write mode to read and write the test signal. |
