Accelerated Graphics Port

Accelerated Graphics Port (AGP) is an obsolete parallel expansion card standard, designed by Intel independently of the PCI-SIG for attaching a video card to a computer system to assist in the acceleration of 3D computer graphics. It was originally designed as a generally compatible successor to PCI-type connections for video cards. The AGP bus was separate from the PCI bus, so that the graphics card as the top consumer of bandwidth in a computer system would not have to compete for bandwidth with other devices, while the overall throughput of the system was greatly increased by the addition of another data bus. The separation also allowed for improvements that broke compatibility with the myriad of existing PCI cards and AGP was not required to be a lowest common denominator standard. The introduction of more efficient queued transactions on top of PCI made it possible for the graphics card to use system memory directly in many circumstances where regular PCI cards required local copies of the data. Since 2004, AGP and PCI were progressively phased out in favor of PCI Express (PCIe). By mid-2008, PCI Express cards dominated the market and only a few AGP models were available, with GPU manufacturers and add-in board partners eventually dropping support for the interface relatively quickly in favor of PCI Express. The analogue of AGP in ISA bus systems was the VESA Local Bus.

Advantages over PCI