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More CGA "even lower res" shenanigans

resman

Veteran Member
Joined
Jan 1, 2014
Messages
526
Location
Lake Tahoe
While looking at a VGA Mode-X image viewer I wrote some time ago, it got me thinking that we're missing some modes on the CGA that should be easy to implement and provide some benefits over the 160x100 16 color lores mode. On the CGA, the next obvious 16 color mode to implement is an 80x50 16 color mode, which has been done. But we're missing something in between: the 100 pixel vertical resolution uses 2 scan lines per character and the 50 pixel vertical resolution uses 4 scan lines per pixel. Where is the 3 scan lines per pixel resolution?


igrnd2_000.png
Enter 80x68 16 color mode. Granted it's only slightly higher resolution than the 80x50, but every bit helps here. As the CGA normally displays 200 scan lines per screen, this resolution pushes that slightly to 204 scan lines. I played around from 64 to 70 vertical pixels and this seemed the best tradeoff while still working well with my composite monitors. A couple of nice features of this mode:

  • No CGA snow (based on 40 column text mode)
  • Double (even triple) buffering available
I've included the code, but be forewarned this was a Saturday afternoon hack job based on an incomplete ground texturing study I did six years ago. I don't plan on doing anything with this soon, but decided to throw it out there in case anyone was interested.
 

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