power-on self-test
     
         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
     
     
see also:
personal computer system board memory diskette hard disk drive cd-rom 
beep operating system boot hung 120 reset 
big red switch power cycle