Datasheet

Signal Description
R
38 Datasheet
Signal Name Type Description
GSTOP# I/O
AGP
G_STOP#: Stop.
During PIPE# and SBA Operation: This signal is not used during PIPE#
or SBA operation.
During FRAME# Operation: G_STOP# is an input when the GMCH/MCH
acts as a FRAME#-based AGP initiator and is an output when the
GMCH/MCH acts as a FRAME#-based AGP target. G_STOP# is used for
disconnect, retry, and abort sequences on the AGP interface.
GDEVSEL# I/O
AGP
G_ DEVSEL#: Device Select.
During PIPE# and SBA Operation: This signal is not used during PIPE#
or SBA operation.
During FRAME# Operation: G_DEVSEL#, when asserted, indicates that a
FRAME#-based AGP target device has decoded its address as the target
of the current access. The GMCH/MCH asserts G_DEVSEL# based on the
DDR SDRAM address range being accessed by a PCI initiator. As an
input, G_DEVSEL# indicates whether the AGP master has recognized a
PCI cycle to it.
GREQ# I
AGP
G_REQ#: Request.
During SBA Operation: This signal is not used during SBA operation.
During PIPE# and FRAME# Operation: G_REQ#, when asserted,
indicates that the AGP master is requesting use of the AGP interface to run
a FRAME#- or PIPE#-based operation.
GGNT# O
AGP
G_GNT#: Grant.
During SBA, PIPE# and FRAME# Operation: G_GNT#, along with the
information on the ST[2:0] signals (status bus), indicates how the AGP
interface will be used next. Refer to the AGP Interface Specification,
Revision 2.0 for further explanation of the ST[2:0] values and their
meanings.
GAD[31:0] I/O
AGP
G_AD[31:0]: Address/Data Bus.
During PIPE# and FRAME# Operation: The G_AD[31:0] signals are used
to transfer both address and data information on the AGP interface.
During SBA Operation: The G_AD[31:0] signals are used to transfer data
on the AGP interface.
GCBE#[3:0] I/O
AGP
Command/Byte Enable.
During FRAME# Operation: During the address phase of a transaction,
the G_CBE[3:0]# signals define the bus command. During the data phase,
the G_CBE[3:0]# signals are used as byte enables. The byte enables
determine which byte lanes carry meaningful data. The commands issued
on the G_CBE# signals during FRAME#-based AGP transactions are the
same G_CBE# command described in the PCI 2.2 specification.
During PIPE# Operation: When an address is enqueued using PIPE#, the
C/BE# signals carry command information. Refer to the AGP 2.0 Interface
Specification, Revision 2.0 for the definition of these commands. The
command encoding used during PIPE#-based AGP is different than the
command encoding used during FRAME#-based AGP cycles (or standard
PCI cycles on a PCI bus).
During SBA Operation: These signals are not used during SBA operation.