| 摘要 |
PURPOSE:To execute and control a program corresponding to changed contents without interrupting processing by providing the titled device with an original PROM and also the 2nd PROM for storing an indication bit or the like at the change of the contents of said PROM as an auxiliary PROM. CONSTITUTION:A microprogram execution circuit 50 executes a microprogram MP1 or MP2 latched by a latch circuit 40 and accesses the PROM10 and PROM20 on the basis of an address signal AD of a program to be executed successively. When the PROM20 is not mounted on its mounting area 21, the MP1 is automatically executed in a loop consisting of PROM10 selector 30 latch circuit 40 execution circuit 50 PROM10. When the PROM20 is mounted on the area 21 and change is generated in the MP1, the MP2 to be a changing program is automatically executed in a loop consisting of RPOM20 selector 30 latch circuit 40 execution circuit 50 PROM20.
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