Specifications

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Chapter 15 Video Hardware
through additional code added to the VGA BIOS chip itself (the more common solution). The benefit
of the VESA BIOS extension is that a programmer needs to worry about only one routine or driver to
support SVGA. Various cards from various manufacturers are accessible through the common VESA
interface. Today, VBE support is a concern primarily for real-mode DOS applications, usually older
games, and for non-Microsoft operating systems that need to access higher resolutions and color
depths. VBE supports resolutions up to 1280×1024 and color depths up to 24-bit (16.8 million colors),
depending on the mode selected and the memory on the video card. VESA compliance is of virtually
no consequence to Windows versions 95 and up. These operating systems use custom video drivers
for their graphics cards.
Note
For a listing of VESA BIOS modes by resolution, color depth, and scan frequency, see “VESA SVGA Standards” in the
Technical Reference portion of the disc accompanying this book.
Integrated Video/Motherboard Chipsets
Although built-in video has been a staple of low-cost computing for a number of years, until the
late 1990s most motherboard-based video simply moved the standard video components discussed
earlier in this chapter to the motherboard. Many low-cost systems—especially those using the semi-
proprietary LPX motherboard form factor—have incorporated standard VGA-type video circuits on
the motherboard. The performance and features of the built-in video differed only slightly from
add-on cards using the same or similar chipsets, and in most cases the built-in video could be
replaced by adding a video card. Some motherboard-based video also had provisions for memory
upgrades.
√√ See “LPX,” p. 207.
However, in recent years the move toward increasing integration on the motherboard has led to the
development of chipsets that include 3D accelerated video and audio support as part of the chipset
design. In effect, the motherboard chipset takes the place of most of the video card components listed
earlier and uses a portion of main system memory as video memory. The use of main system memory
for video memory is often referred to as unified memory architecture (UMA), and although this memory-
sharing method was also used by some built-in video that used its own chipset, it has become much
more common with the rise of integrated motherboard chipsets.
The pioneer of integrated chipsets containing video (and audio) features was Cyrix (now owned by
VIA Technologies). While Cyrix was owned by National Semiconductor, it developed a two-chip prod-
uct called MediaGX. MediaGX incorporated the functions of a CPU, memory controller, sound, and
video and made very low-cost computers possible (although with performance significantly slower
than that of Pentium-class systems with similar clock speeds). National Semiconductor retained the
MediaGX after it sold Cyrix to VIA Technologies. National Semiconductor went on to develop
improved versions of the MediaGX, called the Geode GX1 and Geode GX2, for use in thin clients (a
terminal that runs Windows and has a high-res display), interactive set-top boxes, and other embed-
ded devices. National Semiconductor sold its information appliance business, including the Geode
family, to Advanced Micro Devices (AMD) in August 2003. AMD currently offers a variety of Geode-
based solutions.
Intel became the next major player to develop integrated chipsets, with its 810 chipset for the
Pentium III and Celeron processors. The 810 (codenamed Whitney before its official release) heralded
the beginning of widespread industry support for this design. Intel later followed the release of the
810 series (810 and 810E) with the 815 series for the Pentium III and Celeron, most of which also fea-
ture integrated video. Currently, Intel offers integrated video for the Pentium 4 and Celeron 4
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