| 摘要 |
PURPOSE:To inform a diagnostic processor of the states of peripheral circuits of a microprocessor by connecting in cascade a holding means for holding the contents of an external register to a scanning path in the microprocessor when the address of the external register coincides with a previously set address. CONSTITUTION:When the microprocessor 1 reads out the contents of an error register 31 and the external error register 4, register numbers are outputted from a microinstruction register 10 to gates 15, 18, a signal indicating the read ing of the external register is outputted from a decoder 12 and the contents of the error register 31 are simultaneously fetched to an accumulator 11 and simultaneously with a register 20, as well. The registers 20, 21 for holding the contents of the external error registers 31, 4 are connected in cascade to the other register group 22 to form a scanning path. Consequently, the diagnostic processor the states of the can be informed of peripheral circuits of the microprocessor. |
