Compaq 4000N - Manual (Page 132)

Chapter 6 Graphics Subsystem
Compaq Deskpro 4000N and 4000S Personal Computers
First Edition - September 1997
6-4
6.2.3 S3 TRIO64V2/GX GRAPHICS SUBSYSTEM PROGRAMMING
The S3 Trio64V2/GX is compatible with software written for VGA, EGA, and CGA modes.
Drivers are supplied for control of graphics (GUI) accelerator engines used in extended VGA
modes.
6.2.3.1 Subsystem Configuration
The graphics subsystem works off the PCI bus and is configured through the Trio64V2’s PCI
configuration space registers (listed in Table 6-3) using PCI protocol. These registers are
configured by BIOS during POST to the default configuration.
Table 6–3. GD5436 PCI Configuration Space Registers
Table 6-3.
S3 Trio64V2/GX PCI Configuration Space Registers
PCI Config.
Address
Function
PCI Config.
Address
Function
00h-03h Vender ID (5333h)/Device ID (8901h) 10h-13h I/O Base Address
04h, 05h PCI Command 30h, 31h Expansion ROM Base Address
08h, 09h Status 3Ch, 3Dh Interrupt Line / Interrupt Pin
For a discussion of accessing PCI configuration space registers refer to chapter 4. For a detailed
description of registers refer to the S3 Trio64V2-GX Manual.
6.2.3.2 Subsystem Control
Tables 6-4 and 6-5 list the control registers of the S3 Trio64V2/GX. For a detailed discription of
the control registers refer to appropriate S3 documentation.
Table 6–4. Standard VGA Mode I/O Mapping
Table 6-4.
Standard VGA Mode I/O Mapping
I/O
Address
Function
I/O
Address
Function
3B5.00..26h* CRT Controller (mono) 3C6h..3C9h RAMDAC
3BAh VSYNC Control, Display Status 3CAh Read VSYNC Status
3C1.00..14h* Attribute Controller 3CCh Misc. Control, Read
3C2h Misc. Control / Status 3CF.00..08h Graphics Controller
3C5h.00..04h* Sequencer 3D5.00..26h* CRT Controller (color)
-- -- 3DAh VSYNC Control, Display Status (color)
* Index at base minus 1 (i.e., if base is 3B5h, index is at 3B4h.