![](http://datasheet.mmic.net.cn/340000/82865G_datasheet_16452471/82865G_73.png)
74
Intel
82865G/82865GV GMCH Datasheet
Register Description
3.5.22
ACAPID—AGP Capability Identifier Register (Device 0)
Address Offset:
Default Value:
Access:
Size:
A0h–A3h
00300002h
RO
32 bits
This register provides standard identifier for AGP capability.
3.5.23
AGPSTAT—AGP Status Register (Device 0)
Address Offset:
Default Value:
A4–A7h
1F004217h in AGP 2.0 mode
1F004A13h in AGP 3.0 mode
RO
32 bits
Access:
Size:
This register reports AGP device capability/status.
Bit
Descriptions
31:24
Reserved.
23:20
Major AGP Revision Number (MAJREV)—RO.
These bits provide a major revision number of
AGP specification to which this version of GMCH conforms. This field is hardwired to value of
0011b (i.e., implying Rev 3.x).
19:16
Minor AGP Revision Number (MINREV)—RO.
These bits provide a minor revision number of
AGP specification to which this version of GMCH conforms. This number is hardwired to value of
0000 which implies that the revision is x.0. Together with major revision number this field identifies
the GMCH as an AGP Rev 3.0 compliant device.
15:8
Next Capability Pointer (NCAPTR)—RO.
AGP capability is the first and the last capability
described via the capability pointer mechanism and therefore these bits are hardwired to 0 to
indicate the end of the capability linked list.
7:0
AGP Capability ID (CAPID)—RO.
This field identifies the linked list item as containing AGP
registers. This field has a value of 0000_0010b assigned by the PCI SIG.
Bit
Descriptions
31:24
Request Queue (RQ)—RO.
Hardwired to 1Fh to indicate that a maximum of 32 outstanding AGP
command requests can be handled by the GMCH. This field contains the maximum number of
AGP command requests the GMCH is configured to manage.
23:16
Reserved.
15:13
ARQSZ—RO.
This field is LOG2 of the optimum asynchronous request size in bytes minus 4 to be
used with the target. The master should attempt to issue a group of sequential back-to-back
asynchronous requests that total to this size and for which the group is naturally aligned.
Optimum_request_size = 2 ^ (ARQSZ+4).
Hardwired to 010 to indicate 64 B
12:10
CAL_Cycle—RO.
This field specifies the required period for GMCH initiated bus cycle for
calibrating I/O buffers. Hardwired to 010, indicating 64 ms.
9
Side Band Addressing Support (SBA)—RO.
Hardwired to 1, indicating that the GMCH supports
side band addressing.
8:6
Reserved.
5
Greater Than Four Gigabyte Support (GT4GIG)—RO.
Hardwired to 0, indicating that the GMCH
does not support addresses greater than 4 GB.