BIOS
BIOS or Basic Input/Output System is the first program accessed by the processor during start up to ensure that all the other basic programs, hard drives, ports, peripherals and the central processing unit are in good working condition. BIOS is different from the computer's operating system. The operating system resides in the hard drive and provides the user interface that can be seen on the screen after start up. The BIOS program, on the other hand, can be found right in a flash memory chip or
ROM located in the motherboard. It is the basic requirement for booting a computer.
BIOS Functions
BIOS has several functions in a computer but its most important task is to load the operating system. BIOS provides the microprocessor its first instructions upon activating the computer. The instructions of the BIOS to the microprocessor during start up are the following: power on self test which tests the operating status of all the hardware in the computer, activation of other BIOS chips in some other computer components like
SCSI and graphics cards, checking and management of computer peripherals through low level routines during the start-up process, and management of clock, hard drive and other settings.
BIOS Sequence
The usual sequence of the BIOS program during start up begins with checking the
CMOS setup for any customized settings, loading the device drivers and interrupt handlers of various computer hardware, initializing power management and registers, performing the self test for power, displaying the system settings, determining the bootable devices in the computer, and initiating the boot sequence.
Changing Settings through CMOS
To change the settings in a CMOS setup, a certain key or a certain combination of keys must be pressed during the initial start up sequence. The instructions for this can usually be found at the bottom of the first screen display during the start up process. Upon entering the CMOS set up, several options are available to the user. Setting the system date and time as well as changing the boot sequence, plug and play settings, driver configurations, memory settings, password settings, and power settings are just some of the settings that can be changed on this page.
Updating BIOS
BIOS, especially on older computers, can be updated from time to time. This is so the BIOS program can recognize new devices that have just been recently manufactured. To upgrade or change a computer's BIOS, a special program from the BIOS manufacturer is needed. The BIOS update used must match the original BIOS variant.
The update is done by checking BIOS revision and date information provided on the screen during start up and comparing this with the update list in the BIOS manufacturer's website. The upgrade usually comes with a utility program but sometimes the update can be downloaded separately. This utility program and update must be copied into a floppy disk and inserted into the disk drive the next time your computer boots. This will erase the old BIOS program and install the new one.