How do VGA cards use the C000 memory segment.

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Article #43665

#43665

From: John Wright/Dr. Pat Lane
Date: Thu, 08 Mar 1990 00:56

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I have a Renaissance GRX RVGA I VGA card on a 386 with 2 Meg running
DOS 4.01 and with 386MAX installed.

According to 386MAX, I have a ROM BIOS extension at C000-C400 which
seems resonable (I beleive this is typical for a VGA).  However,
386MAX seems confused as to whether there is ROM or RAM at C400-C800.
Whatever, it won't use that area for high DOS memory.  DEBUG says
there's something at C400-C600 but nothing (FF's) at C600-C800.

How, exactly, is the VGA card using that segment of memory?

BTW, How does this VGA card compare with others.  I beleive it to be
a "plain vanilla" VGA, pretty much IBM compatible and nothing more, no?
Does it use one of the common VGA chips (Video 7, Tseng labs, etc.)?
Is it a clone of anything other than the IBM version?

Thanks for any info.

-- 
John Wright      //////////////////     Phone:  902-424-3805  or  902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8 
Cdn/Eannet:lane@cs.dal.cdn  Uucp:lane@dalcs.uucp or {uunet watmath}!dalcs!lane
Arpa:lane%dalcs.uucp@uunet.uu.net  Internet:lane@cs.dal.ca

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!cs.dal.ca!lane

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!cs.dal.ca!lane
From: lane@cs.dal.ca (John Wright/Dr. Pat Lane)
Newsgroups: comp.sys.ibm.pc
Subject: How do VGA cards use the C000 memory segment.
Message-ID: <1990Mar8.005657.20100@cs.dal.ca>
Date: 8 Mar 90 00:56:57 GMT
Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada
Lines: 23