Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!hacgate!ashtate!alanw
From: alanw@ashtate (Alan Weiss)
Newsgroups: comp.os.msdos.programmer
Subject: Re: 80286 protected mode programming
Message-ID: <1129@ashton.UUCP>
Date: 21 Aug 90 18:05:59 GMT
References: <BIANCO.90Jul30163028@daffodil.cs.odu.edu> <1990Jul31.024249.1328@water.waterloo.edu>
Reply-To: alanw@ashton.UUCP (Alan Weiss)
Distribution: comp
Organization: Ashton-Tate, Torrance, CA
Lines: 46

In article <1990Jul31.024249.1328@water.waterloo.edu> nmouawad@water.waterloo.edu (Naji Mouawad) writes:
>In article <BIANCO.90Jul30163028@daffodil.cs.odu.edu> bianco@cs.odu.edu
>(David J. Bianco) writes:
>
>>How does one kick the 286 chip into protected mode? I'm using TC++ (but
>>only, as of yet, in TC mode, not TC++ mode), and was hoping to get out
>>of this segmented architecture via the protected mode. Since I dont
>>really care if my program will run in the background of a multitasker
>>or anything, I thought this would be a good solution.  
>
>I don't get it. If you set the processor in protected mode, you kill
>Dos (Are you using Dos ?) and unless you use fancy tricks as the ones used
>by Windows and the like, any interrupt service will not be carried away 
>by DOS. Thus, you're program won't be able to read a file or send a
>character to the printer etc...
>
>Unless you have an operating system that supports the protected mode,
>you can't do much of it... but then again, I may be wrong.
>
>-- 
>         ---------------+-------------------------------------------
>        | Naji Mouawad  |       nmouawad@water.uwaterloo.edu        |

No, you're (partially) correct, Naji.  Once in Protected Mode (286-style),
DOS no longer knows who/what/where you are.  Products such as DOS Merge
(Locus Computing, Inglewood CA) use Unix to control the machine.  Some
operating systems (BTOS/CTOS from Unisys/Convergent) offer a *REAL*
operating system that allows programmers to write protected mode
applications and/or system software using real-mode stubs).

'Course, you could always write your own protected-mode monitor program/
mini-OS to manage the environment (which is what Windows does).

This is not especially easy, but others have done this (Windows, OS/2
with the Compatibility Box, DOS Merge, VP/ix, BTOS/CTOS, DESQview, etc.)

Good luck.

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