| 摘要 |
PURPOSE:To perform self-diagnosis automatically by storing a program, which detects faults of check positions determined previously, in a storage unit and operating the control part, which detect automatically faults according to the program, by off-hook of a telephone set. CONSTITUTION:Storage unit ROM1 connected to CPU1 and auxiliary storage unit RAM1 are connected to control circuit MCC of a public telephone set, and ROM1 and RAM1 are connected to I/O circuit I/O1. A program to detect faults of check positions determined previously is stored in ROM1, and various information required for operations of control circuit MCC are stored in RAM1 successively. Then, each time off-hook signal SH from hook switch H is given to CPU1 through circuit I/O1, the program which is stored in ROM1 and detects faults of check positions is read out according to contents of RAM1 by CPU1, thus performing self-diagnosis of each part connected to circuit I/O1. |
