| Upgrading Video with a Video Acceleration Board |
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6.2 |
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6.2.1 | PCI and AGP types examined |
Newer Pentium systems include an advanced Accelerated
Graphics Port (AGP) interface for video graphics.
Figure 
shows an AGP interface and its position on the motherboard. The AGP
interface is a variation of the PCI (see Chapter 2) bus design that
has been modified to handle the intense data throughput associated
with 3-dimensional graphics.
The AGP specification was introduced by Intel to provide a 32-bit video channel that runs at 66 MHz in basic 1X video mode. The standard also supports two high-speed modes that include a 2X (533 MBps) and a 4X (1.07 GBps) mode. The AGP standard provides for a direct channel between the AGP graphic controller and the computer system main memory, instead of using the expansion buses for video data. This removes the video data traffic from the PCI buses. The speed provided by this direct link permits video data to be stored in system RAM instead of in special video memory. The system board typically has a single slot that is supported by a Pentium/AGP-compliant chipset. System boards designed for portable systems and single-board systems may incorporate the AGP function directly into the board without using a slot connector.
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