| 摘要 |
PURPOSE:To make kinds of counter and multiplexer, which are required for diagnostic control conventionally, needless to reduce the number of additional circuits, by constituting the microinstruction address register and the microinstruction register of the diagnostic control unit by shift registers. CONSTITUTION:A diagnostic control unit is constituted by diagnostic mode control circuit 50, microinstruction address register 20 constituted by a shift register, control memory 30, and microinstruction register 40 constituted by a shift register. In case of the normal execution mode, output 25 to designate the address where an executed instruction is stored is sent by register 20, and microinstruction 31 read out from memory 30 is stored in register 40 as a parallel load mode. When circuit 50 is set to the diagnostic mode, register 20 is set to the shift mode by signal 51, and shift clock 22 and serial data 21 are applied from the external, and data 21 is fetched bit by bit to output the read address for memory 30, and instruction 31 is stored in register 40. |
