Power On Self Test

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A series of tests performed by the computer's BIOS when the computer is first turned on. The tests may differ by computer but typically include the computer's memory, keyboard, and other hardware elements. If everything's OK, the computer will start; if not, the computer will typically beep at you (in code) and/or display a message (usually short with an error number).

The tests performed typically include...

• system board
• memory
• current configuration versus stored configuration
• video
• storage devices (floppy/hard disk/CD drives)

Once the tests are complete the BIOS will typically initiate the loading of the operating system from the primary storage device (usually the first hard drive but could also be the floppy or CD-ROM drive).

More Information

• BIOS FAQ