How BIOS works ?

      The most common makes use of of of Flash memory is for the BIOS of your computer. On virtually every computer available, the BIOS makes positive all the other chips, hard drives, ports & CPU function together.
When you start your computer, the Central Processing Unit (CPU) tries to execute its first instruction; it's to get the instruction from somewhere. It cannot get it from the operating technique because the operating technique is located on a hard drive, the CPU cannot get to it without some instructions that will tell it how.
      The CPU sends control of the PC to the BIOS process.The BIOS is part of a power-on self-test of the computer. This check verifies your PC's hardware before booting. It informs the computer about all the devices that are attached to the PC. The BIOS will also tell you if there is an issue with the PC. It does this by looking for all the known devices & makes positive they are still attached to the computer.
If the BIOS detects an issue in the work of the power on self check, it sends a series of beeps to the computer's speaker. These beeps tell the user of what the issue is. As an example, in the event you video card is not working, the BIOS will sense that it's died or is not installed. The BIOS will send a series of beeps to the PC speaker to let you know there is an issue.
      If everything checks out, the BIOS will activate other BIOS chips on different cards installed on the computer. For example: graphics cards often have their own BIOS chip. It next looks for all the parts & peripheral devices that are attached to your computer. The CMOS memory chip stores the information that is used by the BIOS setup & testing routines.
      If everything is working properly, the BIOS will find all the attached input/output devices & sound a single short beep through the speaker & the computer will boot up as usual.