< hardware > (POST) A sequence of diagnostic tests that are run automatically by a device when the power is turned on.
In a personal computer a typical POST sequence does the following:
- checks that the system board is working
- checks that the memory is working
- compares the current system configuration with that recorded by the PC's configuration program to see if anything 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 installed are working.
When POST is finished, typically it will beep , and then let your operating system start to boot . If POST finds an error, it may beep more than once (or possibly not at all if it is your PC speaker that is broken) and display a POST error message. These messages are often nothing more than a single ominous number. Some common numbers and their meanings 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 is restored to known state, turning the power off and on is a standard way to reset a system whose software has hung . Compare 120 reset , Big Red Switch , power cycle .
(2001-03-30)