Every new PC you will come with the BIOS already installed on the computer’s motherboard. BIOS stands for Basic Input Output System. The BIOS is a small set of programs and software routines on a chip that interacts between the computer hardware, the operating system, and software applications.
When you start your computer, the Central Processing Unit (CPU) tries to execute its first instruction; it has to get the instruction from somewhere. It can’t get it from the operating system because the operating system is located on a hard drive, the CPU can’t get to it without some instructions that will tell it how. The CPU sends control of the PC to the BIOS routine.
The BIOS is part of a power-on self-test of the computer. This test 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 inform you if there is a problem with the PC. It does this by looking for all the known devices and makes sure they are still attached to the computer.
If the BIOS detects a problem during the power on self test, it sends a series of beeps to the computer’s speaker. These beeps inform the user of what the problem is. As an example, if you video card is not working, the BIOS will sense that it has died or is not installed. The BIOS will send a series of beeps to the PC speaker to let you know there is a problem.
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 components and peripheral devices that are attached to your computer.
The CMOS memory chip stores the data that is used by the BIOS setup and testing routines. The CMOS chip (complementary metal-oxide-semiconductor) enables a PC to remember the startup and BIOS information even when the power is removed from the computer. The CMOS chip is located on the computer’s mother board and is always on. A small battery powers the chip when the computer’s power is off.
If everything is working properly, the BIOS will find all the attached input/output devices and sound a single short beep through the speaker and the computer will boot up as usual.
At times it may become necessary to have a computer’s BIOS updated. This is especially true of older computers. As new devices and standards become available, the BIOS needs to change in order to understand the new hardware. Since the BIOS is stored in some form of ROM (read only memory) chip, changing it is harder than upgrading most other types of software.
To change the BIOS you’ll need a special program from the BIOS manufacturer. Look at the BIOS revision and date information that is displayed on a computer startup or check with the computer manufacturer to find out what type of BIOS you have. Then go to the BIOS manufacturer’s website to see if an upgrade is available.
Download the upgrade and a utility program needed to install it. Sometimes the utility and update are combined in a single file. Copy the program and the update onto a floppy disk. Restart your computer with the floppy disk in the drive, the program will erase the old BIOS and writes the new one.
You need to be very careful when upgrading your BIOS. Make sure you are upgrading to a version that is compatible with your computer. Otherwise, you could corrupt the BIOS; this means you won’t be able to boot your computer. One other caution is when the BIOS is being updated do not press any keys or the power until it tells you to. If in doubt, check with your computer manufacturer to make sure you need to upgrade.