| 摘要 |
PURPOSE:To shorten the cycle time of conditional branch microinstructions by reading previously next microinstructions for a case where a conditional branch is made and for a case where the branch is not made, and selecting them according to the decision result of the conditional branch. CONSTITUTION:A next microinstruction address when the branch is not made is set in an address register 1 and supplied to the 1st control storage part 4 through an address selecting circuit 3, and a microinstruction to be executed next when the branch is not made is read out. The value of the address field of a conditional branch microinstruction in an instruction readout register 2 which is being executed is supplied to the 2nd control part 6 and a next microinstruction to be executed when the conditional branch is made is read out. The output of a branch condition decision circuit 8 operates a selecting circuit 5 through a gate 15 to select and stores a next microinstruction in the instruction readout register 2. |
