Article View: comp.sys.ibm.pc
Article #44027Re: How do VGA cards use the C000 memor
From: CUMMINGS
Date: Sun, 11 Mar 1990 21:10
Date: Sun, 11 Mar 1990 21:10
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/* Written 9:26 am Mar 11, 1990 by lane@cs.dal.ca in S55:comp.sys.ibm.pc */
/* ---------- "How do VGA cards use the C000 memor" ---------- */
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.
/* End of text from S55:comp.sys.ibm.pc */
What kind of ROM (PROM, EPROM, EEPROM, etc) is on your VGA card?
If you are right, and your VGA BIOS is from C000-C5FF, then it's
24K large. If your VGA card has a 32Kx8 EPROM on it, they may have only
programmed the first 24K (don't 27xxx EPROMs contain all FFs when erased?)
Probably cheaper to manufacture a card with one slightly larger EPROM than
with 3 smaller ones....
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!mintaka!bloom-beacon!primerd!ENI!S55!CUMMINGS From: CUMMINGS@S55.Prime.COM Newsgroups: comp.sys.ibm.pc Subject: Re: How do VGA cards use the C000 memor Message-ID: <132000041@S55.Prime.COM> Date: 11 Mar 90 21:10:00 GMT References: <5657@<1990Mar8> Lines: 32 Nf-ID: #R:<1990Mar8:-565700:S55:132000041:000:1525 Nf-From: S55.Prime.COM!CUMMINGS Mar 11 21:10:00 1990