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Technical Reference Guide
Compaq Deskpro EXS and Workstation 300 Personal Computers
Featuring the Intel Pentium 4 Processor
First Edition - December 2000
4-5
Not required
The register index (CF8h, bits <7..2>) identifies the 32-bit location within the configuration space
of the PCI device to be accessed. All PCI devices can contain up to 256 bytes of configuration data
(Figure 4-3), of which the first 64 bytes comprise the configuration space header.
Figure 4-3. PCI Configuration Space Mapping
Each PCI device is identified with a vendor ID (assigned to the vendor by the PCI Special Interest
Group) and a device ID (assigned by the vendor). The device and vendor IDs for the devices on
the system board are listed in Table 4-1.
Data required by PCI protocol
Configuration
Space
Header
PCI Configuration Space Type 1
Class Code
Command
31 24 23 16 15 8 7 0
Revision ID
Vendor ID
Status
Device ID
Ex
p
ansion ROM Base Address
Reserved
Prefetchable Limit U
pp
er 32 Bits
Prefetch. Mem. Limit Prefetch. Mem. Base
Prefetchable Base U
pp
er 32 Bits
Device-Specific Area
Line SizeLat. Timer
Int. LineInt. Pin
BIST Hdr. T
yp
e
Pri. Bus #Sec. Bus #Sub. Bus #2
n
d
00h
Register
Index
04h
08h
0Ch
2Ch
30h
FCh
18h
28h
3Ch
38h
34h
40h
Brid
g
e Control
I/O Base U
pp
er 16 BitsI/O Limit U
pp
er 16 Bits
24h
20h
Memor
y
BaseMemor
y
Limit
I/O BaseI/O LimitSecondar
y
Status
1Ch
10h
Base Address Registers
00h
Register
Index
04h
08h
0Ch
2Ch
30h
FCh
10h
28h
3Ch
38h
34h
40h
Command
31 24 23 16 15 8 7 0
Revision ID
Vendor ID
Status
Device ID
Reserved
Reserved
Ex
p
ansion ROM Base Address
Subs
y
stem Vendor IDSubs
y
stem ID
Card Bus CIS Pointer
Device-Specific Area
Line SizeLat. Timer
Int. LineInt. PinMin. GNTMin. Lat.
BIST Hdr. T
yp
e
Class Code
Base Address Registers
PCI Configuration Space Type 0