PC/Apple/etc. Cards Worth Keeping/Storing

[Jim Leonard]

Tony Duell wrote:
> What do you need to know? If it's not too much, I can look it up in my 
> techrefs...

Well, nothing that probably already hasn't been stated before -- I know the 
specifications of the Motorola 6845 and how it works, and I know that the tech 
ref documents each CRTC register, etc...  what I'm looking for is stuff that 
probably isn't in the tech ref, like "what are the invalid settings for each 
register", etc as implemented on the CGA.

I say this because, to prove a point to a few of my colleages, I'm writing a 
program that does unholy things with CGA that it were probably never intended 
by the hardware designers.  In addition to writing code for "approved" uses 
like 160x200x16 (composite) and the "third" red-cyan-white palette (disable 
color burst), I'm trying to see just how much it can do.  I've got working code 
for 160x100x16 (tweaked text), 60Hz full-screen horizontal scrolling via the 
address CRTC registers, all 16 colors onscreen in all graphics modes, etc. but 
I recall some rumors about 256-byte-wide modes, undoing the display memory 
interleaving, and some other stuff that I can't confirm/deny.  In other words, 
stuff that the MC6845 can do but the hardware implementation of CGA can't (or 
can if doing something "undocumented"!).
-- 
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/