Hardware Reference
In-Depth Information
Similar to the system BIOS, the video adapter's BIOS takes the form of a read-only
memory (ROM) chip containing basic instructions that provide an interface between the
videoadapterhardwareandthesoftwarerunningonyoursystem.Thesoftwarethatmakes
calls to the video BIOS can be a standalone application, an operating system (OS), or the
main system BIOS. The programming in the BIOS chip enables your system to display
information onthemonitorduringthesystem POSTandbootsequences, beforeanyother
software drivers have been loaded from disk.
See
“
BIOS Basics
,
”
p. 251
(
Chapter 5
,
“
BIOS
”).
In a few cases (primarily with older video hardware), the video BIOS also can be up-
graded, just like a system BIOS. The video BIOS normally use a rewritable chip called
an electrically erasable programmable read-only memory (EEPROM). On old cards, you
might be able to completely replace the chip with a new one—again, if supplied by the
manufacturer and if the manufacturer did not hard-solder the BIOS to the printed circuit
board. Most video cards use a surface-mounted BIOS chip rather than a socketed chip. A
BIOSyoucanupgradeusingsoftwareisreferredtoasa
flash
BIOS,andmostvideocards
that offer BIOS upgrades use this method. However, because the video BIOS is only used
during startup for VGA emulation, such upgrades are rarely necessary, and most vendors
fix problems by issuing updated drivers rather than BIOS updates.
Note
Video BIOS upgrades are sometimes referred to as
firmware upgrades
.
The Video Processor
The video processor (also known as the video chipset, video graphics processor, or GPU)
is the heart of any video adapter and essentially defines the card's functions and perform-
ance levels. Two video adapters built using the same chipset will have the same basic
capabilities. However, cards built using the same chipset can vary in the clock speeds at
which they run the chipset, memory, and other components, as well as in the amount and
typeofmemoryinstalled.Therefore,performancecanvary.ThesoftwaredriversthatOSs
and applications use to address the video adapter hardware are written primarily with the
chipset in mind. You can normally use a driver intended for an adapter with a particular
chipset on any other adapter using the same chipset, or the same chipset families.
Identifying the Video and System Chipsets
Beforeyoupurchaseasystemoravideocard,youshouldfindoutwhichchipsetthevideo
card or video circuit uses. For systems with integrated chipset video, you need to find out
which integrated chipset the system uses. This allows you to have the following:
