Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!snorkelwacker!ai-lab!rpk
From: rpk@wheaties.ai.mit.edu (Robert Krajewski)
Newsgroups: comp.windows.ms
Subject: DOS Apps under Enhanced Mode
Keywords: DOS, 386, V/86
Message-ID: <9755@rice-chex.ai.mit.edu>
Date: 7 Aug 90 23:36:15 GMT
Organization: MIT AI Lab, Cambridge, MA
Lines: 21

Umm, I thought that if you were running Windows in enhanced mode,
it implemented DOS compatiblity by using the V86 mode of the
386 (and newer) processors.  Doesn't that mode allow you to:

1. Put the 1M address space of the V86 inside a virtual memory system

2. Map various segments of memory of the V86 machine in such a way
that the task is unaware that it might be use sharing what it thinks
are well-known hardware resources, like the display adapter, etc.

So, running DOS apps in enhanced mode should not require significant (>
100k) regions of contiguous memory.

I'm not sure how much Windows exploits these capabilities; it seems
like you should be able to share DOS and the BIOS to a certain extent,
and thus free up memory in the DOS boxes.  However, Windows is
supposed to run with a variety of OEM DOSes and BIOSes, so Microsoft
probably doesn't do all that it can to be clever.
-- 
Robert P. Krajewski
Internet: rpk@ai.mit.edu ; Lotus: robert_krajewski.lotus@crd.dnet.lotus.com