Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpfcso!hpcndpc!jjw
From: jjw@hpcndpc.CND.HP.COM (Jimmy Wright)
Newsgroups: comp.os.msdos.apps
Subject: Re: MS-DOS v5.0 Release Date 11th June
Message-ID: <31620005@hpcndpc.CND.HP.COM>
Date: 10 Jun 91 17:32:45 GMT
References: <b6a4pw.hvy@wang.com>
Organization: HP Colorado Networks Division
Lines: 25

>>DOS 5.0 has (of all things), a task manager similar to Windows. Also, the
>>limited docs I have don't mention the filename necessary for Windows and
>>DOS to function together. I will chat with MS and see what I can see,
>>

> WINA20.386

> It has something to do with A20 gating (to access "high" memory) in
> virtual 8086 mode on 386 machines.

	WINA20.386 is a Windows 3.0 Virtual Device Driver (VxD) that is
	loaded by the DOS Kernel when Windows 3.0 is started up in
	386 Enhanced Mode.  A20 refers to enabling the 20th address
	line to enable DOS applications to use the first 64K of 
	extended memory while still running in Real Mode or in this
	case virtual 8086 mode.

	Whenever Windows loads in Enhanced mode it make a broadcast
	that a TSR can intercept.  At this time the TSR can do
	something if it needs to to enable it to run in the Windows
	environment.  Evidently the DOS kernel must load this
	VxD.  If it can't find it then it complains and aborts the
	loading of Windows.

	JJ