power-on self-test
power-on self-test
(hardware)In a personal computer a typical POST sequence does thefollowing:
- checks that the system board is working
- checks that the memory is working
- compares the current system configuration with thatrecorded by the PC's configuration program to see ifanything has been added or removed or broken
- starts the video operation
- checks that the diskette drive, hard disk drive,CD-ROM drive, and any other drives that may be installedare working.
When POST is finished, typically it will beep, and thenlet your operating system start to boot. If POST findsan error, it may beep more than once (or possibly not at allif it is your PC speaker that is broken) and display a POSTerror message. These messages are often nothing more than asingle ominous number. Some common numbers and theirmeanings are:
161 Dead battery(get a new battery for the system board)
162 Configuration changed(you added some memory or a new card to the PC)
301 Keyboard error(take the book off the corner of the keyboard)
Because a successful POST indicates that the system isrestored to known state, turning the power off and on is astandard way to reset a system whose software has hung.Compare 120 reset, Big Red Switch, power cycle.