Preventing CGA revisionist history

Jim Leonard trixter at
Thu Jan 19 14:58:07 CST 2006

Christian Groessler wrote:
> Does anyone on this list know how to enable this mode, or better, has
> a demo program which does that?

It's text mode, ironically.  You enable 80-col textmode and then quarter 
the character cell height with a few port writes to get "80x100" with 
the top two scanlines of every character cell showing.  Then you just 
use ASCII 221 and 223 (the "left half" and "right half" blocks), et 
voila:  160x100 in 16 colors.

I wrote a CGA library last year in pascal+asm and will be putting it 
online with screenshots and photos in an effort to help emulator 
authors; I'll post the URL here when I'm finished.
Jim Leonard (trixter at  
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