| 摘要 |
PURPOSE:To directly inspect the part of a ROM at the time of a shipment check by outputting the microinstruction codes in parallel out of the ROM storing microinstructions to a shift register and outputting the contents of said codes in series via an output port. CONSTITUTION:An instruction code supplied from an instruction code input port 1 is outputted to a ROM 3 from an address generating circuit 4 in the form of an address of 8 bits. Then '1' is inputted to a write signal input port 13 in a state where 0 is inputted to the port 1. A shift register 10 is set in a write mode and the microinstruction code in an address 0 of the ROM 3 is written into the register 10. Then 0 is inputted to the port 13 and the register 10 is set in a shift mode. Thus the microinstruction codes are outputted in series for each bit through an output port 12. Then the codes 0, 1, 2... are inputted successively and repetitively through the port 1. In such a way, the microinstruction codes can be successively read out at and after an address 0 of the ROM 3. |
