When you first turn on your computer, it is all ready to work-but there are no programs loaded into the system memory yet. To solve this problem, there is the BIOS, or basic input/output systems. This is actually a type of software that is encoded within the computer's read-only memory (ROM) chip located on the motherboard. This is to make sure that the BIOS is never altered and to make sure that it will always be available for the central processing unit to use when the computer is first turned on.
Functions of the BIOS:
The most important job of the BIOS is to give the microprocessor its first instructions and to load the operating system when the computer is turned on. It then performs a POST, or power-on self test. This is an inspection to check that everything in the computer is working and functioning properly.
In addition, there is more than one BIOS in your computer. The one commonly referred to is the main system BIOS. However, there are other BIOS chips that can be found in many of your computer's peripherals. The system BIOS activates all of the other BIOS chips.
If everything is found to be working properly during the POST, the BIOS will then try to boot the computer from the hard drive. This is the process of launching the operating system so that you can use many different computer programs, like playing games or surfing the Internet!
Sometimes, errors occur during the booting sequence. For instance, if there is a floppy disk left in the drive when you turn your computer on, you might get an error screen asking you to remove the disk. Of course, this is an easy problem to fix. All you need to do is press a button and take the disk out!
When you turn your computer on:
2. The BIOS checks the CMOS for the settings that you have specified for your operating system (such as background, font, etc.). CMOS is an acronym for Complementary Metal Oxide Semiconductor. It is a RAM chip that stores basic information about your computer system and your configurations. The BIOS will check this to find out the type of hard drive and floppy disks in the computer, how much memory there is, etc.
3. The BIOS loads interrupt handlers, which are software that act like translators, and the device drives, which are software identifying hardware components like a keyboard, mouse, hard drisk, and floppy disk. It will check the ports to make sure these devices are in tact.
4. The BIOS performs the POST to make sure that everything is working properly.
5. It will display system settings.
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