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2 System Board
Accelerated Graphics Port (AGP) Controller
Accelerated Graphics Port (AGP) Controller
The AGP technology was developed as a means to access system memory as
a viable alternative to augmenting the memory of the graphics subsystem
needed for high quality 3D graphics applications. All models of HP Kayak
XU PC Workstations support an AGP (Accelerated Graphics Port) slot.
The AGP bus is based upon a 66 MHz, 32 Bit PCI bus architecture, to which
several signal groups have been added. These additional signals allow to
implement AGP specific control and transfer mechanisms, which are:
• Pipelining and sideband addressing. These control mechanisms in-
crease the bus efficiency compared to the PCI protocol.
• Double clocking (2x mode). This is a transfer mechanism that doubles
the peak transfer rate to 528 MB/s, as two 32 Bit words are transferred in
each clock period (2 x 32
bits x 66 MHz).
AGP specific transactions always use pipelining. The other two mechanisms
can combine independently to pipelining, which leads to these operating
modes:
• FRAME based AGP. Only the PCI protocol is used: 66 MHz, 32 Bits, 3.3V,
264 MB/s peak transfer rate.
• 1 X AGP with pipelining, sideband addressing can be added: 66 MHz, 32
Bits, 3.3V, increased bus efficiency, 264 MB/s peak transfer rate.
• 2 X AGP with pipelining, sideband addressing can be added: 66 MHz dou-
ble clocked, 32 Bits, 3.3V, increased bus efficiency, 528 MB/s peak trans-
fer rate.
The HP Kayak XU PC Workstation fully supports all AGP 1.0 operating
modes.
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