| 摘要 |
PURPOSE:To perform the display of usage disable in case of failure, by storing the program to execute the detection of failure for inspected positions predetermined to the memory unit and automatically performing self-diagnosis with off-hook. CONSTITUTION:The control circuit MCC consists of the processor CPU1, ROM1, RAM1 and I/O1, and the program to perform the detection of failure for predetermined inspected positions is stored in ROM1. Ahead the use of a telephone, when OFF-HOOK is made,the signal SH from the hook switch H is given to CPU1 via I/O1 and since output is made with SH for the power supply circuit PW, MCC is operated and CPU1 clears all the addresses of RAM1 resets the output signals SPW- PRK via I/O1 to set the initial condition. Next, CPU1 reads out the program from ROM1 and executes the detection of failure at inspected positions. |
