| 摘要 |
PURPOSE:To shorten the access time by performing the changeover between the addresses given from an address register and those given from an arithmetic register through a switching circuit and supplying those addresses to a control storage. CONSTITUTION:The loading programs stored in a ROM area of a control storage CS22 are read out successively by the addresses given from an address register PSA20 and sent to an operation register OP23. The addresses which are written to the CS22 of a microprogram muPG read out of an EPROM29 are set to arithmetic registers X25 and Y24. A multiplexer 21 performs the changeover between the addresses sent from the PSA20 and those sent from both registers X25 and Y24 and supplies them to the CS22. Then a program loading instruction is read out and at the same time the muPG read out of the EPROM29 is written to a RAM area of the CS22. Thus the access time is shortened with use of a high-speed RAM and a program can be changed partly and easily. |
