Technical Reference Guide
Compaq Personal Computers
Original – April 1998
G-5
G.4 PROGRAMMING
G.4.1 CONFIGURATION
The graphics card works off the AGP bus and is configured through PCI configuration space
registers using PCI protocol. These registers (Table G-2) are configured by BIOS during POST
Table G–2.
SGS nVIDA RIVA 128 PCI Configuration Space Registers
Table G-2.
NVIDIA RIVA 128 PCI Configuration Space Registers
PCI Config.
Address Function
PCI Config.
Address Function
00h Vender ID/Device ID 14h Relocateable I/O Base Address
04h PCI Command 30h Expansion ROM Base Address
08h Status 3Ch Interrupt Line / Interrupt Pin
10h Display Memory Base Address -- --
For a discussion of accessing PCI configuration space registers refer to chapter 4. For a detailed
description of registers refer to applicable NVIDIA Corp. documentation.
G.4.2 CONTROL
Table G-3 list the control registers used for operating in standard VGA mode. No special drivers
are required for VGA, EGA, and CGA modes. For a detailed description of the registers refer to
applicable NVIDIA documentation.
Table G–3.
Standard VGA Mode I/O Mapping
Table G-3.
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.
Extended mode registers (display and configuration, GUI, multimedia, and PLL registers) may be
I/O or memory-mapped and are controlled through the supplied graphics driver.
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