ATI Rage 128

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The ATI Rage 128 is a series of graphics cards from the late 1990s. It's noteworthy as a candidate for device driver development as the Rage 128 Pro is emulated in QEMU.

Models sharing this register programming interface include:

ATI Rage 128 VR
ATI Rage 128 GL
ATI Rage 128 Pro
ATI Rage 128 Ultra
ATI Rage Fury MAXX

It has the usual three compatibility programming modes, which won't be discussed further here:

Apart from that, it has its own programming mode exposed on the PCI/AGP bus. This is what the rest of this article will focus on.

We will focus on the 2D framebuffer and 2D drawing engine.

Getting a 2D Framebuffer

Prerequisites: PCI Bus Probing, knowledge of VGA signal timing.

Basically, you want to do the following things:

Detect the card via PCI and read BAR0 (framebuffer memory) and BAR2 (memory mapped I/O). BAR1 can be ignored as it just provides a subset of BAR2.
(Optional) enable AGP speed
If using paging, map the MMIO and framebuffer into accessible address space.
Enable the accelerator CRTC (rather than VGA CRTC).
Set the CRTC with VGA timings that will work.
Start drawing pixels

CRTC Setup

For a 1024x768x32 screen:

// Set horizontal total width and display width.
regs[CRTC_H_TOTAL_DISP]=0xD0|(0x7F<<16);
// Set horizontal sync start, width, and polarity.
regs[CRTC_H_SYNC_STRT_WID]=(0x82<<2)|(0x31<<16)|(1<<23);
// Set vertical total width and display width.
regs[CRTC_V_TOTAL_DISP]=0x325|(0x2FF<<16);
// Set vertical sync start, width, and polarity.
regs[CRTC_V_SYNC_STRT_WID]=(0x302)|(0x26<<16)|(1<<23);
// Set number of bytes per line.
regs[CRTC_PITCH]=1024*4;
// Enable accelerator CRTC, switch off VGA CRTC, set 32bpp mode.
regs[CRTC_GEN_CTRL]=(6<<8)|(1<<24)|(1<<25);

These values are (mostly) from page E-8 of the Rage Pro (NOT 128 Pro) programmer's guide, but corrected for the newer 128 hardware. Make your own on the Video Signals And Timing page.

These CRTC values work in QEMU but have not (yet) been tested on real hardware.

ATI Rage 128

Getting a 2D Framebuffer

CRTC Setup

See Also

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