IBM PC hacking

[Jim Leonard]

Chris M wrote:
> 
>  I find the 400 line graphic cards the most
> interesting. Sigma 400, STB, Tecmar, Taxan, and others

My AT&T PC 6300 (Olivetti M24 clone) had this but it wasn't as exotic as the 
hardware mentioned above:  The stock Motorola 6845 character generator (MC6845) 
was used, but it just pointed to an 8x16 character table so you got nicer 
characters in 400-line mode.  200-line modes were just scanline-doubled.  Pro? 
  a true 640x400-line high-res mode.  Con?  Games that used text character 
"graphics" (that took the stock IBM 8x8 font into account when they were 
created) didn't look right.

Oh, another favorite feature:  The card had a signal line that could activate 
the degaussing circuit on the bundled AT&T monitor.  I almost fell out of my 
chair when I ran diagnostic software that printed something like 
"Degaussing..." and then was quickly followed by a loud noise and the familiar 
"twisty pix" distortion of a monitor in its degaussing cycle...  scared the 
crap out of me.
-- 
Jim Leonard (trixter at oldskool.org)                    http://www.oldskool.org/
Want to help an ambitious games project?             http://www.mobygames.com/
Or check out some trippy MindCandy at             http://www.mindcandydvd.com/