BIOS performs power-on self-test (POST) when the computer is turned on. This test ensures that the computer is functioning properly and also gathers information about what the computer contains. When the problem is identified during POST, BIOS usually produce an error message. However, in certain cases the problem is detected very early in the test itself that the BIOS cannot even access the video card to print the message. In such cases the BIOS will produce a beeping pattern on the speaker to let you know of the problem.
The exact meaning of the beep codes depends on the make and version of BIOS that you have. The three most popular types of BIOS available in the market are:
Award
American Megatrends (AMI)
Phoenix
If you are using a computer made by a company that makes its own BIOS, you will have to see your owner's manual or the company's web site or other technical information for assistance.
Note: If your computer gives a single beep during the boot process, it is normal and does not indicate a failure as long as the boot continues on.
