Abstract: A personal computer, wherein a setup processing is performed to select a display mode, either a normal-display mode or a reverse-display mode, and also to select one of the external devices such as a printer and an external floppy disk drive. Also, a display auto-off mode and a display auto-off period are set during the setup processing. A period is measured during which no data is input from a keyboard. When the measured time value exceeds the display auto-off period, the supplement of power to the back light is stopped automatically.

Abstract: A computer having a resume function and operable on an internal battery is equipped with a circuit for checking the output voltage of the battery and a controller. When the output voltage of the internal battery becomes equal to or less than a predetermined value during data processing, a resume processing is executed for data protection irrespective of whether a resume mode is set ON or OFF, and the content of the data processing in progress is saved. When the output voltage of the internal battery is restored to a level greater than the predetermined value, data processing is resumed based on the saved content.