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Article #319

Finding hardware bios and ram in the dos upper 384k region.

#319
From: Tom Swanson
Date: Tue, 15 Sep 1992 19:27
29 lines
1524 bytes
Hi,

I have a problem.  I need to know how to locate bios and adapters in
the dos upper memory region.

I know that I can look for the hex string 55AA which denotes the start of
bios code followed by the size, in 512 byte chunks, of the bios code.  That 
seems to work.

My first question is -- will this always find every occurance of a bios?

Looking at the output of asq by Quantalis (sp?) there are areas of
RAM on some adapter boards sitting in this upper memory region.  How does 
one go about locating this region?  I presume that is would be very bad to 
simply see if I can write and read out there.  Who knows what it would do
to my peripherals.

My last question (although if anyone with experience in this knows of anything
that I am likely to miss in this area let me know) is how do I know which
regions of memory (between A0000 and C0000) are ACTUALLY used by my video 
card?

I prefer an email answer to toms@digibd.com, but I'll take the info where
I can get it.

Thanks,
	TomS

I suppose I should have a signature here.
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Message-ID: <1992Sep15.192712.20270@digibd.com>
Path: arc1-ca.pugleaf.net!sparky!uunet!digibd!toms

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Newsgroups: alt.msdos.programmer
Path: arc1-ca.pugleaf.net!sparky!uunet!digibd!toms
From: toms@digibd.com (Tom Swanson)
Subject: Finding hardware bios and ram in the dos upper 384k region. 
Organization: DigiBoard Incorporated, Eden Prairie, MN
Date: Tue, 15 Sep 1992 19:27:12 GMT
Message-ID: <1992Sep15.192712.20270@digibd.com>
Summary: I need to know how to locate the open spaces in upper memory. 
Keywords: upper memory, bios
Sender: toms@digibd.com
Lines: 30