82845G Datasheet, PDF (30/193 Pages) Intel Corporation – Intel 82845G/82845GL/82845GV Graphics and Memory Controller Hub (GMCH)

Signal Description
2.4.3 AGP Status Signals
2.4.4
Signal Name
GST_[2:0]
Type
O
AGP
Description
Status: GST_[2:0] provide information from the arbiter to an AGP Master on
what it may do. GST_[2:0] only have meaning to the master when its GGNT#
is asserted. When GGNT# is deasserted, these signals have no meaning and
must be ignored. GST_[2:0] are always an output from the GMCH and an
input to the master.
000 = Previously requested low priority read data is being returned to the
master
001 = Previously requested high priority read data is being returned to the
master.
010 = The master is to provide low priority write data for a previously queued
Write command.
011 = The master is to provide high priority write data for a previously queued
Write command.
100 = Reserved
101 = Reserved
110 = Reserved
111= The master has been given permission to start a bus transaction. The
master may queue AGP requests by asserting PIPE# or start a PCI
transaction by asserting FRAME#.
AGP Strobes
Signal Name
GADSTB_0
GADSTB_0#
GADSTB_1
GADSTB_1#
GSBSTB
GSBSTB#
Type
I/O (s/t/s)
AGP
I/O (s/t/s)
AGP
I/O (s/t/s)
AGP
I/O (s/t/s)
AGP
I
AGP
I
AGP
Description
GAD Bus Strobe-0: This signal provides timing for 2X and 4X clocked data on
GAD_[15:0] and GC/BE_[1:0]#. The agent that is providing data drives this
signal.
GAD Bus Strobe-0 Complement: GADSTB_0# is the differential complement to
the GAD_STB_0 signal. It is used to provide timing for 4X clocked data.
GAD Bus Strobe-1: This signal provides timing for 2X and 4X clocked data on
GAD_[31:16] and GC/BE_[3:2]#. The agent that is providing data drives this
signal.
GAD Bus Strobe-1 Complement: GADSTB_1# is the differential complement to
the GADSTB_1 signal. It is used to provide timing for 4X clocked data.
Sideband Strobe: This signal provides timing for 2X and 4X clocked data on the
GSBA[7:0] bus. It is driven by the AGP master after the system has been
configured for 2X or 4X clocked sideband address delivery.
Sideband Strobe Complement: GSBSTB# is the differential complement to the
GSBSTB signal. It is used to provide timing for 4X clocked data.
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Intel^® 82845G/82845GL/82845GV GMCH Datasheet