| 摘要 |
<p>PURPOSE:To protect a memory of a microcomputer and at the same time to maintain the state secured before a service interruption occurs when the service interruption is recovered and the power is supplied again, by providing a means which saves the internal state of a central processing unit to a random access memory in case a commercial power supply has a service interruption. CONSTITUTION:When a commercial power supply has a service interruption, the service interruption detecting signal is produced at a service interruption detecting part 3. This service interruption detecting signal is fed to a CPU1 and a reset signal reducing part 15. The CPU1 saves the internal state of the CPU1 to RAMs (3a-3n). A power supply switching part 10 performs a switch so that the power is supplied to the RAMs (3a-3n) from a battery 9. Thus these RAMs receive the power supply from the battery 9, and the contents of RAMs are protected with no volatilization. When the service interruption is recovered, the generation of the service interruption signal is stopped to release the resetting of the CPU1. In this case, the internal state of the CPU1 saved to the RAMs before the service interruption occurs is reset to the CPU1. As a result, the state secured before the service interruption can be maintained.</p> |
