power-on self-test
(foldoc) | power-on self-test
POST
(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)
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