Pci Configuration - Compaq Deskpro EP 6233 Technical Reference Manual

Chapter 4 System Support
4.2.7

PCI CONFIGURATION

PCI bus operations, especially those that involve ISA bus interaction, require the configuration of
certain parameters such as PCI IRQ routing, top of memory accessable by ISA, SMI generation,
and clock throttling characteristics. These parameters are handled by the PCI/ISA bridge
function (PCI function #0) of the south bridge component and configured through the PCI
configuration space registers listed in Table 4-6. Configuration is provided by BIOS at power-up
but re-configurable by software.
Table 4–6. PCI/ISA Bridge Configuration Registers (82371, Function 0)
PCI Config.
Addr. Register
00, 01h Vendor ID
02, 03h Device ID
04, 05h Command
06, 07h Status
08h Revision ID
09-0Bh Class Code
0Eh Header Type
4Ch DMA Aliasing Control
4E-4Fh APIC/BIOS Control
60h PCI Interrupt Routing
61h PCI Interrupt Routing
62h PCI Interrupt Routing
NOTE: Assume unmarked locations/gaps as reserved.
4-10 Compaq Deskpro EP Series of Personal Computers
Table 4-6.
PCI/ISA Bridge Configuration Registers
(82371, Function 0)
Reset PCI Config.
Value Addr.
8086h 63h
7111h 64h
69h
6A, 6Bh
76, 77h
80h
82h
00h 90, 91h
0003h 92, 93h
80h 94, 95h
80h B0-B3h
80h CBh
First Edition - April 1998
Register
PCI Interrupt Routing
Serial Interrupt Control
Memory Map Control
SERR-/PCI Cycle Retry
DMA Enable/Ch. Routing
A12 Mask/X-Y Base Addr.
USB Passive Rel. Enable
DMA Channel Select
DMA 0-3 Base PTR
DMA 4-7 Base PTR
GPIO/Misc. Funct. Select
RTC/RAM Control
Reset
Value
80h
02h
00h
00h
00h
00h
00h
00h
00h
21h