
VT8601 Apollo ProMedia
Revision 1.3 September 8, 1999
-33-
Register Summary Tables
7HFKQRORJLHV ,QF
:H&
:H&RRQQHFW
QQHFW
Miscellaneous I/O
One I/O port is defined in the ProMedia: Port 22.
Port 22 – PCI /AGP Arbiter Disable ...............................RW
7-2
Reserved
........................................ always reads 0
1
AGP Arbiter Disable
0
Respond to GREQ# signal .....................default
1
Do not respond to GREQ# signal
0
PCI Arbiter Disable
0
Respond to all REQ# signals..................default
1
Do not respond to any REQ# signals, including
PREQ#
This port can be enabled for read/write access by setting bit-7
of Device 0 Configuration Register 78.
Configuration Space I/O
All registers in the ProMedia (listed above) are addressed via
the following configuration mechanism:
Mechanism #1
These ports respond only to double-word accesses. Byte or
word accesses will be passed on unchanged.
Port CFB-CF8 - Configuration Address......................... RW
31
Configuration Space Enable
0
Disabled ................................................. default
1
Convert configuration data port writes to
configuration cycles on the PCI bus
30-24 Reserved
........................................ always reads 0
23-16 PCI Bus Number
Used to choose a specific PCI bus in the system
15-11 Device Number
Used to choose a specific device in the system
(devices 0 and 1 are defined)
10-8 Function Number
Used to choose a specific function if the selected
device supports multiple functions (only function 0 is
defined).
7-2
Register Number (also called the "Offset")
Used
to
select
a
specific
DWORD
in
the
configuration space
1-0
Fixed
........................................ always reads 0
Port CFF-CFC - Configuration Data.............................. RW
Refer to PCI Bus Specification Version 2.2 for further details
on operation of the above configuration registers.