| 摘要 |
PURPOSE:To reduce the quantity of hardware by using one RAM decoder by plural pieces of ROM decoders in common. CONSTITUTION:The storage system is constituted by providing plural pieces of ROMs 8A to 8N in which the microprograms are stored, a RAM 11 part in which the optional microprogram can be stored, a means 6 to hold write-in data to the RAM 11 part, the means 5 to hold a write address to the RAM part, the means 7 to control write-in to the RAM part, the means 1A to 1N to hold read addresses corresponding to the ROM parts, the means 12 to switch the read address corresponding to the ROM part and use it as the read address of the RAM part, the means 13A to 13N to switch the output of the ROM part and the output of the RAM part, and the means 12 to control the switching means. Thus, the quantity of the hardware can be reduced.
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