| 摘要 |
PURPOSE:To prevent the steal of a program, by feeding a part of the program to a volatile RAM to make it difficult to reproduce the program. CONSTITUTION:An RAM7 which is volatile and has a small stand-by current is provided in addition to an RAM4. A battery 9 is connected to the RAM7 via a resistance 8, and at the same time the resistance 8 is connected to a power supply line 5 via a diode 10. A program is fed to an ROM3 but not all of it, and an optional address is extracted. Then a part of the extracted address is fed to a part of the RAM7. The program of the RAM7 is supplied by a writing device 11 during the shipment of the program. The RAM7 is always affected by the voltage of the battery 9. |
