Data protection device for a computer of an engine control

A data protective apparatus for an engine control system based on computer control comprises a circuit 4 for detecting a power supply voltage for the computer 1, a delay circuit 5 responsive to an output signal from the voltage detection circuit to produce a delay signal having a first predetermined time delay relative to the output signal, and a reset circuit 6 responsive to the delay signal from the delay circuit to produce a reset signal having a second predetermined time delay relative to the delay signal. When the power supply voltage for the computer is decreased, data in the computer are saved into another store 2 during the first time delay immediately prior to resetting of the computer by the reset signal. Thereafter the computer is reset, and the resetting is released at expiration of the second time delay following recovery of the power supply voltage.