| 摘要 |
PURPOSE:To efficiently use a register, by tracing a microinstruction address only when the re-evaluation of information required for tracing work is performed and an instruction is a conditional branch instruction and also conditional branch succeeds. CONSTITUTION:A trace register 10 stores the microinstruction address to trace the execution address of a microprogram. And it stores the microinstruction read out from a control storage in a microinstruction register 2, and decodes the microinstruction stored in the above stated microinstruction register by a microinstruction decoder 3. A conditional branch decision circuit 4, when the microinstruction from the microinstruction decoder being the conditional branch instruction, sends a signal representing the fact to a control part 5. The control part 5 receiving the signal performs decision of the success of the conditional branch, and writes the conditional branch instruction or the microinstruction address in the neighborhood of the instruction on the register 10 when the success is obtained.
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