| 摘要 |
PURPOSE:To improve the yield of a microprocessor at the time of manufacture by using a microprogram which does not use the operation defective part of a constituting element as the content of a controlling storage. CONSTITUTION:It is arranged that an initializing and loader programs are respectively stored in the 1st and 2nd ROMs 3 and 4 and they are selectable by means of external signals 2. Usually the ROM3 is selected by the signal 2 after power supply is made and the initializing program and instruction are read out to a microinstruction register 5. The read out program and instruction is decoded by a decoder 6 and executed. When a bit fault is found in, for example the 1st register R1 of an internal register group 8 by a testing means (out of the figure), the ROM4 is selected by the signal 2 and initialization of each section and the loading operation of a microprogram into a controlling storage 9 are performed, and then, a microinstruction which uses the register R1 is changed to, for example, the 2nd register R2. Therefore, a defective product can be relieved.
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