3. POST

• What is a POST?

  • power-on self-test -- one of the first processes that a computer undergoes when booting

  • POST tests the computer to ensure that it is working as it is supposed to.

  • POST can detect some errors with the processor, motherboard, RAM and other memory, as well as the video card.

  • Most BIOS chips use a system of beep codes to indicate the POST status to the user and each BIOS chipset uses a different code.

  • The IBM PC BIOS code standard, for example, uses one short beep to indicate a successful POST and two short beeps to indicate a POST error while AMI BIOS uses these same beep codes to indicate a DRAM refresh failure or parity circuit failure, respectively.