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Technical Reference Guide
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
4-7
Not required
Table 4–4. PCI Function Configuration Acces
Table 4-4.
PCI Function Configuration Access
PCI Function Device No. Function No.
Host/PCI Bridge (82443) 0 0
PCI/AGP Bridge (82443) 0 1
PCI/ISA Bridge (82371) 20 0
IDE Interface (82371) 20 1
USB Interface (82371) 20 2
Power Management Cntlr. (82371) 20 3
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 (see Figure 4-4), of which the first 64 bytes comprise the configuration space
header.
Figure 4–4. PCI Configuration Space Map
Each PCI device is identified with a vender ID (assigned to the vender by the PCI Special Interest
Group) and a device ID (assigned by the vender). The device and vender IDs for the devices on
the system board are listed in Table 4-5.
00h
Configuration
Space
Header
Vender ID
Data required by PCI protocol
Base Address Registers and Exp. ROM Address
Register
Index
31
Cache Line Size
Latency Timer
Device ID
Command
Status
Revision IDClass Code
Header T
y
pe
BIST
Device-Specific Area
Interrupt LineInterrupt PinMin_GNTMin_Lat
24 23 16 15 8 7 0
04h
08h
0Ch
3Ch
40h
FCh