Supported Cards, RAMDACs, and Bits Per Pixel

Notes for Mach32 X Server : Supported Cards, RAMDACs, and Bits Per Pixel
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## 1. Supported Cards, RAMDACs, and Bits Per Pixel

The base support in the Mach32 X server is for 8 bpp, with a dot clock of up to 80 MHz. At present 15/16 bpp is supported on only three of the many RAMDACs; however those three cover the most commonly sold cards.

     RAMDAC      Max Dot Clock   BPP   Max Resolution   Video RAM Required
    --------     -------------   ---   --------------   ------------------
    Default           80MHz       8      1280x1024i            2Mb
    Default           80MHz       8      1024x768              1Mb

    ATI68875         135MHz       8      1280x1024             2Mb
    ATI68875          80MHz      16      1024x768              2Mb

    AT&T20C49x        80MHz       8      1024x768              1Mb
    AT&T20C49x        40MHz      16       800x600              2Mb

    BT481             80MHz       8      1024x768              1Mb
    BT481             40MHz      16       800x600              2Mb

The RAMDAC is reported when you run the Mach32 X server with the "`-probeonly`" command line option, or can be specified in the XF86Config file.

The ATI68875 (or the TLC34075) is used on the Graphics Ultra + and the Graphics Ultra Pro. The Brooktree 481 is used on most Graphics Wonder cards. The AT&T20C491 is used on many of the OEM cards that are built into component systems.

The BIOS detection unfortunately lumps the BT481 and the AT&T20C49x together, while they require different configuration controls in 16 bit mode. SuperProbe can tell the difference, and will report which it finds. In the server itself, the BT481 is considered the default value. If you have an AT&TC49x RAMDAC on your card you will have to include the Ramdac entry in the XF86Config file as below.

Notes for Mach32 X Server : Supported Cards, RAMDACs, and Bits Per Pixel
Previous: Notes for Mach32 X Server
Next: XF86Config options