| 摘要 |
PURPOSE:To easily set an address designating range by using an index register holding a register address, a mask register having the same number of bits as the index register, and a masked increment circuit. CONSTITUTION:A constant (i) given from an instruction by SETRAR signals is set to a register address register RAR6 and the output of the RAR6 is decoded and selected by a register Ri. The contents of the register Ri are set to a register data register RDR2 by the SETDR signal. The RDR2 inputs to a masked increment circuit 3 and writes again the value 8 obtained by applying the masked increment to index data 1 with the SETGR signal. Both EN and SETRAR signals are produced at a time and the data 1 or the 8 are set to the RAR6 according to 0 or 1 of the sign data S. Then the contents of the RAR6 are read and written as the register number of an operand according to an instruction code.
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