4 Additional Notes

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If you have a RAMDAC that is not listed here, be VERY careful not to overdrive it using XF86_S3. Better contact the XFree86 team first to verify that running XF86_S3 will not damage your board.

If you feel adventurous you could also open up your computer and have a peek at your RAMDAC. The RAMDAC is usually one of the larger chips (second or third largest chip that is NOT an EPROM) on the board. The markings on it are usually

  <Company logo>

      <company identifier><part number>-<speed grade>
      <manufacturing week><manufacturing year>  
      <lot number><other funny numbers>

For example:

          @@
          @@ AT&T

        ATT20C490-11
         9339S ES
          9869874

This is an AT&T 20C490 with a speed grade of 110 MHz. This would then mean that you put a `DacSpeed 110' line in your XF86Config file. Be advised that some RAMDACs have different modes that have different limits. The manufacturer will always mark the chip naming the higher limits, so you should be careful. The S3 server knows how to handle the limits for most of the RAMDACs it supports providing the DacSpeed is specified correctly.

Chips labeled -80 or -8 should use `DacSpeed 80' in the device section.

S3 86C716-ME SDAC  ==>  DacSpeed 110
SC15025-8          ==>  DacSpeed  80
ATT20C490-80       ==>  DacSpeed  80

IBM 8190429        ==>  DacSpeed 170
IBM 03H5428        ==>  DacSpeed 170
IBM 03H6447        ==>  DacSpeed 170
IBM 03H6448        ==>  DacSpeed 220
IBM 03H5319        ==>  DacSpeed 220
IBM 63G9902        ==>  DacSpeed 250

IBM 37RGB514CF17   ==>  DacSpeed 170
IBM 37RGB524CF22   ==>  DacSpeed 220
              ^^

Some RAMDACs (like the Ti3025) require some mode timing consideration for their hardware cursor to work correctly. The Ti3025 requires that the mode have a back porch of at least 80 pixel-clock cycles. A symptom of this not being correct is the HW cursor being chopped off when positioned close to the right edge of the screen.

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