BIOS

BIOS (pronounced /ˈbaɪoʊs/), in computing, stands for Basic Input/Output System.[1] [2]
The term is incorrectly known as Binary Input/Output System, Basic Integrated Operating System and occasionally Built In Operating System. BIOS refers to the firmware code run by an IBM PC when first powered on. The primary function of the BIOS is to identify and initiate component hardware (such as hard disk, floppy and optical disk drives). This is to prepare the machine so other software programs stored on various media can load, execute, and assume control of the PC.[3] This process is known as booting, or booting up, which is short for bootstrapping.
BIOS can also be said to be a coded program embedded on a chip that recognizes and controls various devices that make up x86 personal computers. Among other classes of computers, the generic terms boot monitor, boot loader or boot ROM were commonly used. Some Sun and Macintosh PowerPC computers used Open Firmware for this purpose. There are a few proposed alternatives for Legacy BIOS in the x86 world: Extensible Firmware Interface, Open Firmware (used on the OLPC XO-1) and coreboot.
The term first appeared in the CP/M operating system, describing the part of CP/M loaded during boot time that interfaced directly with the hardware (CP/M machines usually had a simple boot loader in ROM, and nothing else). Most versions of DOS have a file called "IBMBIO.COM" or "IO.SYS" that is analogous to the CP/M disk BIOS.