| 摘要 |
PURPOSE:To obtain a microprogram controlling device from which the quantity of hardware can be reduced, by commonly using a RAM for state hysteresis data and fault diagnostic program. CONSTITUTION:When a stopping condition such as fault is detected in a microprogram controlling device, the controlling device is stopped and the program reading out sequence from a ROM1 and state hysteresis data writing sequence to a RAM2 are also stopped. At this time, a log routine stored in the ROM1 is started and a swtich 7 is switched to a receive the output of the RAM2. A microinstruction CMD sets an FF17 to a set condition and a RAM controlling circuit 18 outputs the designation signal of a minum access mode to a counter 3. Accordingly, the counter 3 successively subtracts ''1'' from its holding content at the time of stoppage and the address of the RAM2 designated by the holding content of the counter 3 is read out by an external service processor, etc., through the switch 7, a reading out register 21, and data bus 9.
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