Last month right before FOSDEM 2008, the 3D programming documentation for the R500 GPUs (Radeon X1000) series was released. This documentation consisted of a register reference guide for the R500 GPUs as well as a programming guide covering such areas as the command processor, vertex shaders, and fragment shaders. While the register reference guide for the R600 series is still being worked on, for those with older ATI graphics processors, AMD has went back and created a register reference guide for the R300 series.

Today's R300 documentation release is just 99 pages long but covers registers for color buffer, fog, geometry assembly, graphics backend, rasterization, clipping, setup unit, texture, fragment shaders, vertex, and Z-Buffer. This is now the fourth open-source documentation dump (and sixth document) from AMD, since announcing their open-source strategy last year. Aside from the R500 3D guide, the previous documents had covered the basic register information for the R500/600 mobile and desktop chipsets (RV630/M56 and M76/RS690).

AMD is going back and releasing this information for the pre-R500 GPUs in order to fix and fill in the existing areas of the R300 support in the xf86-video-ati driver and to help explain the programming differences compared to the R500 series. The R300 open-source support had largely been reverse-engineered and built upon the R200 open-source support, which came from documentation ATI had released to open-source developers under Non-Disclosure Agreements several years ago. The Radeon R300 series consists of such graphics cards as the Radeon 9500, 9800, X300, X550, and X600 -- both AGP and PCI Express parts. Phoronix