Path: utzoo!attcan!uunet!van-bc!mdivax1!mitchell
Newsgroups: alt.sources.wanted
Subject: CGA video reverser
Message-ID: <1990Sep20.142939.238@mdivax1.uucp>
Date: 20 Sep 90 14:29:39 GMT
Reply-To: mdivax1!mitchell%mdi.com (Bill Mitchell)
Organization: Mobile Data International, Richmond, B.C., Canada
Lines: 13
Return-Path: <mdivax1!news>
Apparently-To: van-bc!rnews

Can anyone point me towards or send me a utility to reverse the
mochrome images displayed on a CGA?

Let me clarify that a bit.  Recently, I've been viewing GIF files
on a laptop (CGA w/ B&W LCD) and a desktop (CGA w/ color).  Images
displayed as normal mochrome images on the desktop are displayed
as negative images on the laptop, and I'd like to invert them.

I haven't looked into this myself, but it seems as if my GIF viewer 
(gifdot) might be using BIOS calls and, if so, these could be
intercepted and the data twiddled on the way in.  Alternatively,
perhaps the CGA hardware provides some mode control mechanism which
could be fiddled with.