Purposes and functions of BIOS

BIOS (Basic Input/Output System) is a program for the initial boot of a computer, equipment adjustment and input/output functions support.

BIOS is recorded on the flash-memory microcircuit which is located on the mainboard. Initially, the main purpose of BIOS was input/output devices maintenance (keyboard, screen and disk drives); that is why it was called “Basic Input/Output System”. BIOS performs several functions in modern computers:

  • boot and procedure of self-testing (Power-On Self Test, POST). A program, located in BIOS microcircuit, loads the first after computer power-up. It detects and examines the installed equipment, adjusts it and prepares for the future operation. If the equipment failure occurs, POST procedure will stop operating and corresponding message or alarm will be revealed;
  • system parameters setting with the BIOS Setup program assistance. During the procedure POST equipment adjusts within the parameters that are stored in the specific CMOS-memory. Users can configure separate devices and entire system at their own discretion by violating these parameters which are edited in a special program called BIOS Setup or CMOS Setup. The majority of our articles will be dedicated to a system setup with the assistance of BIOS Setup program;
  • input/output functions support with the assistance of BIOS program interrupts. System BIOS comprised of built-in functions for the manipulation with keyboard, video display adapter, disk drive mechanisms, hard disk drives, input-output ports, etc. These functions have been used in such operation systems as MS-DOS, and they are almost not used in Windows modern versions.