Altera PCI Compiler - Manual (Page 123)

Altera Corporation User Guide Version 11.1 3–49
October 2011
Functional Description
4. The PCI MegaCore function drives and asserts devseln (and
ack64n
for 64-bit transactions) to indicate to the master device that
it is accepting the transaction.
5. One or more data phases follow, depending on the type of read
transaction.