PC/Apple/etc. Cards Worth Keeping/Storing

Jim Leonard trixter at oldskool.org
Fri Apr 29 22:36:27 CDT 2005

Tony Duell wrote:
>>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...

Considering that the 160x200 composite color mode was actually documented, that 

> 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/
Or check out some trippy MindCandy at             http://www.mindcandydvd.com/

More information about the cctalk mailing list