HP Kayak XU 04xx HP Kayak XU PC Workstation Technical Reference Manual Hardwar - Page 31

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 double clocked, 32 Bits, 3.3V, increased bus efficiency, 528 MB/s peak transfer rate. The HP Kayak XU PC Workstation fully supports all AGP 1.0 operating modes. 23