| 摘要 |
PURPOSE:To elevate the reliability and workbility of an equipment, by suppressing the subsequent execution by a hardware means, when the contents of a fundamental area and a control register have been rewritten by mistake, by executing a microprogram which has been prepared by a user. CONSTITUTION:1 word of a microprogram which has been read out from the control memory device 1 is set to the fields F1-F3 of the contol register 4. Also, the device is made a fundamental area and a firmware area, and a specific microinstruction by which the contents of the fundamental area used in the firmware, and the register 4, etc. are rewritten by mistake is defined as a privilege microinstruction. And, the privilege microinstruction of each field F1-F3 is discriminated by the microinstruction discriminating circuits 6-8, and an output signal S4 is made ''1'' and is output from the OR gate 9. Also, an output signal S0 of the firmware area, which has been discriminated by the address discriminating circuit 5 is provided to the AND gate 10 together with the signal S4, and when there is a privilege microinstruction, it is suppressed to execute the subsequent instruction by the microinstruction execution suppressing circuit 11. |
