Datasheet

Signal Description
R
Datasheet 37
2.3.5 AGP/PCI Signals-Semantics
For transactions on the AGP interface carried using AGP FRAME# protocol these signals operate
similarly to their semantics in the PCI 2.1 specification, as defined below.
Table 9. AGP/PCI Signals-Semantics Descriptions
Signal Name Type Description
GFRAME# I/O
AGP
G_FRAME: Frame.
During PIPE# and SBA Operation: Not used by AGP SBA and PIPE#
operations.
During Fast Write Operation: Used to frame transactions as an output
during Fast Writes.
During FRAME# Operation: G_FRAME# is an output when the
GMCH/MCH acts as an initiator on the AGP Interface. G_FRAME# is
asserted by the GMCH/MCH to indicate the beginning and duration of an
access. G_FRAME# is an input when the GMCH/MCH acts as a FRAME#-
based AGP target. As a FRAME#-based AGP target, the GMCH/MCH
latches the C/BE[3:0]# and the AD[31:0] signals on the first clock edge on
which GMCH/MCH samples FRAME# active.
GIRDY# I/O
AGP
G_IRDY#: Initiator Ready.
During PIPE# and SBA Operation: Not used while enqueueing requests
via AGP SBA and PIPE#, but used during the data phase of PIPE# and
SBA transactions.
During FRAME# Operation: G_IRDY# is an output when GMCH/MCH
acts as a FRAME#-based AGP initiator and an input when the GMCH acts
as a FRAME#-based AGP target. The assertion of G_IRDY# indicates the
current FRAME#-based AGP bus initiator's ability to complete the current
data phase of the transaction.
During Fast Write Operation: In Fast Write mode, G_IRDY# indicates that
the AGP-compliant master is ready to provide all write data for the current
transaction. Once G_IRDY# is asserted for a write operation, the master is
not allowed to insert wait states. The master is never allowed to insert a
wait state during the initial data transfer (32 bytes) of a write transaction.
However, it may insert wait states after each 32-byte block is transferred.
GTRDY# I/O
AGP
G_TRDY#: Target Ready.
During PIPE# and SBA Operation: Not used while enqueueing requests
via AGP SBA and PIPE#, but used during the data phase of PIPE# and
SBA transactions.
During FRAME# Operation: G_TRDY# is an input when the GMCH/MCH
acts as an AGP initiator and is an output when the GMCH/MCH acts as a
FRAME#-based AGP target. The assertion of G_TRDY# indicates the
target’s ability to complete the current data phase of the transaction.
During Fast Write Operation: In Fast Write mode, G_TRDY# indicates
the AGP-compliant target is ready to receive write data for the entire
transaction (when the transfer size is less than or equal to 32 bytes) or is
ready to transfer the initial or subsequent block (32 bytes) of data when the
transfer size is greater than 32 bytes. The target is allowed to insert wait
states after each block (32 bytes) is transferred on write transactions.