| 摘要 |
PURPOSE:To use the same data for the source input to an arithmetic circuit constituted of one bus and storage in an external register by forming an external register storing field in a microinstruction. CONSTITUTION:When a microinstruction 4 is executed, the contents of a floating register (FR) 11 specified by an external register address field 41 are read out and inputted to the arithmetic circuit (ALU) 2 and a work register (WR) 21 and the processing is executed. When operation source data are inputted from the FR 11 to an operation part as a source input, the data can be also stored in a shift register (SR) 12 which is an external register specified by an external register storing field 42. Even if whether the operation source data value is a normalized number or not is indistinct when the arithmetic unit is a floating point arithmetic unit, checking operation in the operation part and transfer operation to the shift register (SR) 12 for executing shift operation necessary for the succeeding normalizing processing can be executed only by one microinstruction.
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