| 摘要 |
PURPOSE:To correct a program stored in a ROM with high efficiency by providing a comparison means which performs the comparison between the address data received via an address bus and the address data received from an address data zone and transmits a command signal when the coincidence is obtained between both address data. CONSTITUTION:When a program stored in a ROM 5 has a defect, a defective area correcting program is written into a 1st nonvolatile memory 19. Then a write/read circuit 20 writes the address of the defective area into the address data zone 21A of a 2nd nonvolatile memory 21. Simultaneously, the instruction data corresponding to the address of the defective area and to jump to the memory 19 is written into a data zone 21B. When the address of the defective area is called out, a comparator 22 outputs a command signal and the jump instruction data is selected by an instruction data selecting circuit 23 and outputted. Then a corrected program is carried out. Thus, the defect of the program stored in the ROM 5 can be easily corrected. |
