| 摘要 |
PURPOSE:To decrease the number of steps of a microprogram by using the contents of a microinstruction qualifying register to qualify the contents of a microinstruction register when the microinstruction is changed and then producing a hardware control command to be supplied to an arithmetic processing part. CONSTITUTION:A microprogram read out of a control memory 1 is held by a microinstruction register 2 and then applied to an arithmetic processing part 3 as a hardware control command 2A. Here the three bits of 0-th, 1-th and 2-th of the register 2 undergo the special processing. When the bit 2 is equal to '1', the contents of the register 2 are delivered as they are to the part 3 via a qualifying circuit 6 as the hardware control commands 4A and 4B. While the contents of the register 2 are replaced with the contents of a microinstruction qualifying register 5 by the circuit 6 and sent to the part 3 when the bit 2 is equal to '0'. In such a way, a microprogram that attains different functions can be obtained effectively with a small number of steps.
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