Abstract: Writing to an EEPROM when the regulated supply voltage to the EEPROM is below a minimum voltage required for proper operation is prevented by determining the battery voltage threshold which corresponds to the minimum required supply voltage, measuring the battery voltage and the rate of change of voltage and projecting the voltage to the end of the write cycle. When the projected battery voltage is below the threshold the write cycle is canceled. The write cycle is also canceled when the battery voltage is below the normal operating range when a write cycle is requested.

Abstract: A vehicle anti-theft system is equipped with a circuit to produce a pulse signal when a disconnected vehicle battery is reconnected, and a normally asleep microcomputer based controller is programmed to wake up upon receipt of the pulse signal or another detector signal, and to evaluate the status of each detector signal and the armed, disarmed and alarm state of the controller to sound an alarm, if appropriate, in response to the battery reconnect signal. The armed, disarmed or alarm state of the controller is stored in a non-volatile memory so that information will be kept indefinitely during power loss.