Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!bbn!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!ralf
From: ralf@b.gp.cs.cmu.edu (Ralf Brown)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Problem of breaking DOS 640K RAM limit?
Message-ID: <4443@pt.cs.cmu.edu>
Date: 8 Mar 89 22:00:29 GMT
References: <74032HJW2@PSUVM> <15373@cup.portal.com> <1345@ccncsu.ColoState.EDU> <1429@cfa.cfa.harvard.EDU>
Organization: Carnegie-Mellon University, CS/RI
Lines: 23

In article <1429@cfa.cfa.harvard.EDU> ward@cfa.harvard.EDU (Steve Ward) writes:
}
}So, if you can modify your BIOS you can add at least 128K (must be
}contiguous with the 640K on the motherboard) and bring your memory
}up to 768K.
No you can't, at least if you want to have a video board installed....
CGA starts at 736K, MDA/Herc at 704K, EGA/VGA graphics at 640K.  If you use
only programs that exclusively use BIOS screen writes, and an appropriately
addressed video board (assuming you can find/build one), then and only then
can you get more than 736K contiguous DOS memory.

On an AT, the ALL ChargeCard can play appropriate tricks with the memory 
addressing so that the existing video board looks like it starts at 960K,
but that then requires programs that do BIOS writes or have been patched.
BTW, I have one for sale, it won't work with my Smartek motherboard.... (but
ALL says both cards I sent back work fine on their machines--they couldn't
give me a refund because I didn't buy it directly from them).  Contact me for 
details.
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