Editing Accelerated Graphics Port (section)

===In-band AGP requests using PIPE#===
To queue a request in-band, the card must request the bus using the standard PCI REQ# signal, and receive GNT# plus bus status ST[2:0] equal to <code>111</code>. Then, instead of asserting FRAME# to begin a PCI transaction, the card asserts the PIPE# signal while driving the AGP command, address, and length on the C/BE[3:0], AD[31:3] and AD[2:0] lines, respectively. (If the address is 64 bits, a dual address cycle similar to PCI is used.) For every cycle that PIPE# is asserted, the card sends another request without waiting for acknowledgement from the motherboard, up to the configured maximum queue depth. The last cycle is marked by deasserting REQ#, and PIPE# is deasserted on the following idle cycle.