| 摘要 |
PURPOSE:To modify an emergency program at low cost by using a PROM only for emergency correction and by excluding the PROM once the correction of a mask ROM is completed. CONSTITUTION:Firstly, a correction program module is written in a PROM3 to be packaged in the PRM3. Then, an area for specifying the module name of a defective program in the PROM3 is read to discriminate which module is faulty. The part of the defective module in a mask ROM2 is not executed from the point in time, and a substitute module in the PROM3 is used. In parallel to emergency correction by the PROM, the correction of the mask ROM is also performed and once it is completed, the PROM is excluded. At thie tim, a mode changeover switch is returned to its original position. |
