| 摘要 |
PURPOSE:To easily diagnose a fault with a simple device, by storing the state history data of a microprogram controlling device and a trouble diagnostic program from the outside in a common memory and outputting them by switching as occasion demands. CONSTITUTION:An ROM1 previously stores a microprogram and an RAM2 stores an accessing address to the ROM1 as history data and a trouble diagnostic program supplied from the outside by switching. When this system starts, the diagnostic program stored in the ROM1 is loaded onto the RAM2 and a diagnostic is performed. When no abnormality is found, the system is set to the operating condition. The microinstruction of the ROM1 is successively executed through a register 18 and decoder 19. An FF16 is set by a microinstruction CMD and writing in RAM is appointed 17, and then, the RAM2 writes the state history synchronously to the ROM1. When a fault occurs, the program is stopped and the diagnostic program loading routine of the ROM1 starts, and then, the content of the RAM2 is successively read out in the opposite way. Therefore, trouble diagnoses can be performed even when the quantity of hardware is reduced. |
