RG82855GMESL72L Datasheet, PDF (36/213 Pages) Intel Corporation – Intel® 855GM/855GME Chipset Graphics and Memory Controller Hub (GMCH)

Signal Descriptions
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3.3.4 AGP Strobes
Table 8. AGP Strobe Descriptions
Signal Name
GADSTB[0]
GADSTB#[0]
GADSTB[1]
GADSTB#[1]
GSBSTB
GSBSTB#
Type
I/O
AGP
I/O
AGP
I/O
AGP
I/O
AGP
I
AGP
I
AGP
Description
Address/Data Bus Strobe-0: provides timing for 2X and 4X data on AD[15:0] and
C/BE[1:0]# signals. The agent that is providing the data will drive this signal.
Address/Data Bus Strobe-0 Complement: With AD STB0, forms a differential strobe
pair that provides timing information for the AD[15:0] and C/BE[1:0]# signals. The
agent that is providing the data will drive this signal.
Address/Data Bus Strobe-1: Provides timing for 2X and 4X data on AD[31:16] and
C/BE[3:2]# signals. The agent that is providing the data will drive this signal.
Address/Data Bus Strobe-1 Complement: With AD STB1, forms a differential strobe
pair that provides timing information for the AD[15:0] and C/BE[1:0]# signals in 4X
mode. The agent that is providing the data will drive this signal.
Sideband Strobe: Provides timing for 2X and 4X data on the SBA[7:0] bus. It is
driven by the AGP master after the system has been configured for 2X or 4X sideband
address mode.
Sideband Strobe Complement: The differential complement to the SB_STB signal. It
is used to provide timing 4X mode.
3.3.5 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
GFRAME#
Type
I/O
AGP
Description
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 acts as an
initiator on the AGP Interface. G_FRAME# is asserted by the GMCH to indicate the
beginning and duration of an access. G_FRAME# is an input when the GMCH acts as
a FRAME#-based AGP target. As a FRAME#-based AGP target, the GMCH latches
the C/BE[3:0]# and the AD[31:0] signals on the first clock edge on which GMCH
samples FRAME# active.
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Datasheet