NetNews Usenet Archive 1992 #19/NN_1992_19.iso/spool/comp/sys/ibm/pc/hardware/22736

Internet Message Format | 1992-08-26 | 1.3 KB

Xref: sparky comp.sys.ibm.pc.hardware:22736 comp.os.msdos.programmer:8822
Path: sparky!uunet!mcsun!uknet!daresbury!doc.ic.ac.uk!rhbnc!csqx.cs.rhbnc.ac.uk!adrian
From: [e-mail] (A Johnstone)
Newsgroups: comp.sys.ibm.pc.hardware,comp.os.msdos.programmer
Subject: More on DMA
Message-ID: <[e-mail]>
Date: 26 Aug 92 16:29:28 GMT
Sender: [e-mail] (USENET News System)
Reply-To: [e-mail] (A Johnstone)
Organization: Dept of Comp Sci, Royal Holloway & Bedford New College Uni London
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Nntp-Posting-Host: csqx.cs.rhbnc.ac.uk

Well, my DMA saga continues. Several people told me after my last post that
vanilla MS-DOS does map virtual to physical as in real mode until you start
filling memory up (contrary to what I had claimed). I now have basic DMA
working on a 386, having fixed the timing problem that had been causing the
virtual DMA to fail.

So far, so good, but I still need a `proper' mapped solution for general use,
especially under Windows. Several people (not least Ralf Brown)have drawn my
attention to the existence of the Virtual DMA specification (VDS) which sounds
like just what I want, but beyond the information in Ralf's interrupt listing
nobody seems to know much about it. Can anybody enlighten me, or point me some
documents?

                          Adrian