Additional Notes

# 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 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 a AT&T 490 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

> `

>     S3716-ME SDAC  ==>  DacSpeed 110
>     SC15025-8      ==>  DacSpeed  80
>     ATT20C490-80   ==>  DacSpeed  80

> `

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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