MICROINSTRUCTION CONTROL CIRCUIT

摘要

PURPOSE:To switch a circuit including a defect to a stand-by circuit without any assistant of another extra logical device by using a simple selector and an error display circuit in combination. CONSTITUTION:The error display circuit 21 displays normal/defect states of (K+1) blocks in a microinstruction registers 12 individually and an error mask circuit 20 controls whether inspection results of the respective blocks are transmitted to the circuit 21 or not. A selection decoder 22 outputs a signal for allowing a block shift switching input selector 11 and a block shift switching output selector 13 to change their internal connections to other blocks so that a defective block in the register 12 corresponding to a ''0'' signal meaning an error among (K+1) signals inputted from a signal line 24. When the ''0'' signal is impressed to a control signal line 23, a circuit 20 inhibits the result of parity check from the register 12.