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From: ast@botter.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Request for help with EGA board problem
Message-ID: <1212@botter.cs.vu.nl>
Date: Tue, 16-Jun-87 14:21:15 EDT
Article-I.D.: botter.1212
Posted: Tue Jun 16 14:21:15 1987
Date-Received: Fri, 19-Jun-87 01:27:16 EDT
Reply-To: ast@cs.vu.nl (Andy Tanenbaum)
Distribution: world
Organization: VU Informatica, Amsterdam
Lines: 20

I have been told that it is possible to get an EGA board to act 
like a 16K CGA board by outputting two bytes:
    4 to port 3C4
    1 to port 3C5

I have tried this on the Paradise EGA board, and it doesn't seem to work.

I have some software that directly addresses the CGA card and does its own
scrolling by outputting bytes to the 6845, but with the EGA card it works
funny due to the board not wrapping around at the 16K mark as the CGA card
does.  The screen goes blank and other strange things happen.

If anyone who understands EGA cards (or even anyone who has the manual)
could help, it would be greatly appreciated.  There have been negotiations
with the local dealer for 6 months just trying to get an EGA manual, and
it looks like that will ultimately fail.   

Please reply by e-mail to ast@cs.vu.nl

Andy Tanenbaum