Basic Input/OutputSystem (BIOS) is a mini-operating system of personal computers, notebooks or other computers that contains the firmware and controls the input and output functions of the computer. The BIOS is written in a hardware-oriented programming language and is the actual interface between hardware and software.
The BIOS contains the basic hardware configurations at system startup and loads the operating system. When a computer is turned on, the operating system sends a request to the BIOS. The BIOS is initialized by booting, which performs the POST(Power On Self Test) self-test. Afterwards, the BIOS routines are processed and communication with the hardware components such as keyboard, mouse, drives, hard disk, RAMs and monitor is established.Programmable Read Only Memory (PROM), Erasable PRO M (EPROM) or Electrically Erasable PRO M (EEPROM). This has the advantage that when the personal computer (PC) is shipped, the BIOS is already hard-coded and always available and cannot be corrupted by hard disk errors. The BIOS also ensures that a personal computer can boot itself.