| 摘要 |
PURPOSE:To perform a decimal multiple operation with the same instruction regardless of an operator by using a register to store the designated operator and carrying out successively the operations divided by an arithmetic instruction common with the flag of said register. CONSTITUTION:The instruction code part of an arithmetic instruction M is decoded by a decoder 11 and erases the flag of a flag register 12 via an inverter 13 and an OR circuit 14 to set it at 0 when a processing instruction ABCD instructing the addition of decimals including no positive/negative code is outputted in the form of value '1'. While a flag 1 is set to the register 12 via the circuit 14 when a processing instruction SBCD instructing the subtraction of decimals including no positive/negative code is outputted in the form of '1'. In such a way, a decimal arithmetic circuit carries out successively additions or subtractions in response to the flag state of the register 12 after an arithmetic instruction DCE is received.
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