[OFF TOPIC?] Fixed Freq Monitor Questions

From: J. Maynard Gelinas <maynard_at_jmg.com>
Date: Fri Apr 10 18:29:22 1998

          BTW: no one responded to this message, so I guess no one
       knew the answer. I received a responce to a USENET post about
       this and thought there might be some interest in the group.
       The VGA spec supports 'doublescan' mode for low resolution
       compatability with CGA apps. This essentially forces the card
       to draw each horizontal line twice, thus doubling the refresh
       rate (or your vertical resolution in half at the same refresh
       rate) at any arbitrary horizontal scan rate. Well, some
       chipsets (like the 968, Matrox Millenium, and most ATI
       chipsets), allow for tripplescanning which does exactly what
       one would expect... it scans each horizontal line three times
       before skipping down to the next line, thus allowing one to
       drop down to a third of the vertical resolution at the same
       refresh rate (same horizontal rate always, of course).
          OK. XFree86 and SVGAlib don't support tripplescan mode, but
       they do support doublescan mode because it's part of the VGA
       spec. Tripplescan is vendor specific, and so thus is enabled
       in different ways for each chipset. I'm attempting to hack
       svgalib to support tripplescan for the S3/968... waiting for
       the 968 docs to arrive so I can find the register and register
       values to set for my adapter. The rest seems fairly easy, just
       hack in parsing for 'tripplescan' on the modeline and such.

          Why does this matter to you? Well, if you have an Hitachi
       HM-4119, HP1097C, or somesuch fixed freq monitor, getting it to
       work under Linux is pretty easy once you know the trick. Why
       buy a $1500 monitor when you've got a perfectly fine one
       sitting on your VaxStation 3100? Well, for the purposes of
       this list, why not just use the 3100 as the xterm... but that
       defeats the purpose of this message. ;-)


       [bit 'o original]


       OK, This is mildly on topic. My monitor is an HP 1097C, making
it at least 10 years old. However, I am using it with a modern PC, so
that's where the 'on topic' issue gets a little iffy. I'm sure there
are plenty of people here who can answer this question. A pointer to
a FAQ would be most welcome.
Received on Fri Apr 10 1998 - 18:29:22 BST

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