| 摘要 |
PURPOSE:To change quickly and easily the contents of a microprogram by providing an RAM which can store the microprogram to be changed among those stored in a PROM. CONSTITUTION:When a change is needed to the contents of a microprogram MP1, a selector 21 is set under a B input selection state by a selection signal SL1. Then a write control signal WT is set active to write a microprogram MP2 to be changed to an RAM20 with an address AD2 corresponding to an address to be changed of a PROM10. Then the selector 21 is set again under an A input selection state by the signal SL1, and the reading of the stored MP2 is started to the RAM20. Thus a selector 30 is set automatically under a B input selection state by a selection signal SL2. Therefore the programs are executed successively according to the MP2 stored in the RAM20.
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