More recent operating systems do not use the BIOS interrupt calls after startup. In the era of DOS, the BIOS provided BIOS interrupt calls for the keyboard, display, storage, and other input/output (I/O) devices that standardized an interface to application programs and the operating system. The BIOS in modern PCs initializes and tests the system hardware components ( Power-on self-test), and loads a boot loader from a mass storage device which then initializes an operating system.

The interface of that original system serves as a de facto standard. The BIOS originally proprietary to the IBM PC has been reverse engineered by some companies (such as Phoenix Technologies) looking to create compatible systems. The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. The BIOS firmware comes pre-installed on a personal computer's system board, and it is the first software to run when powered on. In computing, BIOS ( / ˈ b aɪ ɒ s, - oʊ s/, BY-oss, -⁠ohss an acronym for Basic Input/Output System and also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is firmware used to perform hardware initialization during the booting process (power-on startup), and to provide runtime services for operating systems and programs. A pair of AMD BIOS chips for a Dell 310 computer from the 1980s

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