Basic input/output (BIOS) is a type of firmware that permits the hardware of a personal computer to be interfaced with in the absence of any other operating system or software. Where system BIOS performs this function for most of the hardware in a computer, video BIOS is exclusive to video cards. Everything seen on a computer monitor prior to the operating system booting up is created by the BIOS, with the video BIOS providing a way for the video card to be interacted with at that early stage. The video BIOS also includes a basic set of instructions and functions that allows software to interact with the video card at all other times.
Video BIOS has been commonly included on video cards since the early 1980s, when Enhanced Graphics Adapter (EGA) video cards were first introduced. Prior to that time, all video BIOS functions were performed by the system BIOS. The earlier system BIOS was incapable of activating EGA and subsequent chipsets, necessitating their own BIOS. Video cards were subsequently managed by their own video BIOS, while all other hardware continued to be interfaced with via the system BIOS. This included later Video Graphics Array (VGA) and subsequent video cards.
BIOS can typically be accessed at the very beginning of the boot cycle, after a computer is turned on but before the operating system has loaded. This is typically accomplished by pressing a key or a combination of keys and will often present users with a semi-graphical interface. This interface can be used to change certain settings, such as boot order, auto detection of hardware, and allotment of shared random access memory (RAM). Changing certain settings should be done with care, because it may be possible to damage a video card with incorrect BIOS settings.
Performing a BIOS update is sometimes possible, though this process can also damage a video card if done incorrectly. BIOS is firmware that's contained on the video card, so the process involves flashing the new BIOS to the card. If the manufacturer of a video card releases an updated BIOS for a particular card, the BIOS should be available directly from that manufacturer. Similarly, some video cards are capable of using the BIOS released for a more expensive card in the same product line. This sort of BIOS updating can potentially improve the performance of a video card or, in some cases, even add more functionality than the card had out of the box.