| 摘要 |
PURPOSE:To keep assuredly the secret information stored in a memory even in case the normal execution of a program is impossible, by clearing the area of the secret information when a program is loaded. CONSTITUTION:Both the head address and the length of the secret information are set previously to an address memory circuit 50 by a program. When a load detection signal 70 is turned on, a clear circuit 60 produces an address from the contents of an address memory circuit 50 and sets it to an address register 30. At the same time, a write pulse is produced from a clock circuit 40 after a data register 20 is cleared. Then the secret information is cleared. The contents of the register 30 are updated for each execution of said information clearing procedure. The updating processing of the register contents is repeated until the secret information shown by the circuit 50 are all cleared. |
