Chapter 4 System Support
Compaq Deskpro EP Series of Personal Computers
First Edition - April 1998
4-8
Table 4–5. PCI Device Identification
Table 4-5.
PCI Device Identification
PCI Device Vendor ID Device ID [1]
North Bridge (82443 PAC):
Host/PCI Bridge (Function 0) [2]
PCI/AGP Bridge (Function 1)
8086h
8086h
7180h / 7190h
7181h / 7191h
South Bridge (82371 PIIX4):
PCI/ISA Bridge (Function 0)
EIDE Controller (Function 1)
USB I/F (Function 2)
Power Mngmt. Cntlr (Function 3)
8086h
8086h
8086h
8086h
7110h
7111h
7112h
7113h
AGP Graphics Controller [3] [3]
NOTES:
[1] 443EX / 443BX
[2] Graphics Address Remapping Table (GART) utilized on all systems.
[3] Refer to applicable appendix for graphics controller vendor and device IDs.
4.2.3.3
Special Cycles
There are two types of special cycles that may occur on the PCI bus. The first type is initiated by
the host and is used to perform the following functions: Shutdown, Flush, Halt, Write Back,
Flush Acknowledge, Branch Trace Message, and Stop/Grant. These cycles start like all other PCI
cycles and terminate with a master abort.
The second type of special cycle is initiated by writing to 0CF8h, Bus # = all 0s, Device = all 1s,
Function # all 1s, and Register = all 0s) and 0CFCh to generate a Type 0 configuration cycle.
This type 0 cycle, however, does not assert any of the IDSEL lines and therefore results in a
master abort with FFFFh returned to the microprocessor.
4.2.4
OPTION ROM MAPPING
During POST, the PCI bus is scanned for devices that contain their own specific firmware in
ROM. Such option ROM data, if detected, is loaded into system memory’s DOS compatibility
area (refer to the system memory map shown in chapter 3).
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