29 Apr
2005
29 Apr
'05
8:36 p.m.
Tony Duell wrote:
Considering that the 160x200 composite color mode was actually documented, that
stinks!
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.
That is not in the techref :-(. It doesn't even tell you how to get the
160*200 16 colour mode... What, I suspect, you need to do is look at the
schematics. Those are in
the techref, the board consists of a 6845, 16K DRAMs and a lot of TTL.
There's nothing custom (unlike the gate array in the PCjr), so it should
be possible to figure it all out.
Okay, looking at MC6845 specs right now...
Be warned that, of course, clone cards may not support
such tricks.
That's their problem :-) I have a true blue CGA card, so that's what I'm
going
to hammer on.
Thanks for checking for me!
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Want to help an ambitious games project? http://www.mobygames.com/
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