Abstract: Power failure protection for data processing apparatus is provided by the use of a standby power module which supplies power to the data processing apparatus when the normal supply is interrupted. Since damage to the data processing apparatus may result in the event of a sudden power failure, power failure protection software controls the data processing apparatus to cause periodic sampling of the state of the standby power module. During the time that the standby power module is operating, a timer in the data processing apparatus operates to measure the total time that said standby power module has operated since its last recharge. When said total time exceeds a predetermined amount which is based upon the minimum time during which the standby power module can supply power to the data processing apparatus, the power failure protection software initiates an orderly power shutdown of the data processing apparatus, in order to avoid a sudden power loss which might result in damage.