| 摘要 |
PURPOSE:To refer to plural registers by providing a mask register where a mask value for determination of a micro operand address is held in a microprogram controlled information processor. CONSTITUTION:The micro operand address given from a decoding part is transferred to an operand pointer 3 through a signal line 12. A write permission signal INSTBGN 21 is outputted when execution of a preceding software instruction is terminated, and the value of the pointer 3 is settled at the time of the execution of a current software instruction is started. At the time of a mask register 1 is referred, contents of a microprogram latch 2 and the pointer 3 are controlled by the mask value and are used as the micro operand address, and a variable number of registers can be referred thereby, thus reducing the capacity of a control storage and shortening the instruction execution time.
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