Compaq Deskpro AP400 Supplementary Manual page 9

W P
HITE APER
(cont'd)
AGP improves system performance by establishing pipelined access to the system's
main memory and effectively reducing latency. AGP also transfers data up to four times
faster than PCI, utilizing the bandwidth of a 100-MHz system memory bus more
efficiently. The maximum data transfer rate of AGP is 533 MB/s, compared to 133
MB/s for PCI. The bus acts as a dedicated port for the graphics accelerator into main
memory.
CUSTOMER BENEFITS
Some specific applications that can benefit from AGP include:
Video applications, like conferencing or DVD playback, where a steady stream
of images must be sent from system memory to the graphics frame-buffer for
display.
Graphics command lists, such as lengthy data sets defining vertices for 3D
objects
Texture memory for 3D rendering, where textures are overlaid on 3D objects for
realistic effects. To improve realism, texture sizes will grow to 32 MB and
beyond in 1999.
Note: 3D texture data is the most immediate and important target
opportunity for AGP. By shifting texture data to system memory,
bandwidth load and memory size can be balanced between system and
local graphics frame-buffer memory. The bandwidth and space required
for textures are split between the heavily loaded frame-buffer and the
(comparatively) lightly loaded system memory. Since texture data is not
persistent (unlike display buffers), system memory used for texture data
is returned to the free memory heap when a 3D application concludes.
To gain the full benefit of AGP performance, the system must have the following
features:
Pentium II class microprocessors
Note: While AGP could be adapted to Pentium-class processors, the
floating point and processing power of the Pentium II class products are
a better fit.
AGP Sideband and Pipeline functions in the core logic, which improve data
transfer efficiency
100-MHz system memory architecture to meet system processor and AGP
bandwidth demands
Microsoft Windows® 95 OSR2.1, Windows 98, or Windows NT® 5.0 operating
systems to provide necessary memory management services
Note: Windows NT 4.0 can operate AGP subsystems as PCI 66MHz-
type devices only.
AGP promises to enable photo-realistic 3D rendering and other high-performance 3D
graphics capabilities. The cutting edge graphics performance of AGP will benefit 3D
content providers by enabling a much wider market for their products.
Compaq Workstations - Key Technologies
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