| 摘要 |
PURPOSE:To quickly access a memory and to shorten the instruction execution time, by using a conditional memory access micro code to output a memory access signal only when the operand is the memory. CONSTITUTION:The instruction code of a unit length is held in an instruction register 1 and the output is decoded by an instruction code decoder 2. The micro code from a ROM is given to a decoder 3, and a signal B for memory access and a signal C for switching to the next instruction re obtained as the output. The signal C is inputted to an instruction start condition deciding decoder 4 together with an output A of the decoder 2. The decoder 3 outputs a signal D only when receiving the conditional memory access micro code. The signal D is inputted to an AND gate 5 together with the inverted signal of the signal A, and the output is inputted to an OR gate 6 together with the output B, and the output becomes the memory access signal.
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