Path: utzoo!utgpu!watserv1!watmath!att!linac!midway!magrathea!francis
From: francis@magrathea.uchicago.edu (Francis Stracke)
Newsgroups: comp.sys.mac.programmer
Subject: Re: A use for protected mode after all
Message-ID: <1990Nov29.201754.10384@midway.uchicago.edu>
Date: 29 Nov 90 20:17:54 GMT
References: <1990Nov28.031713.14035@maverick.ksu.ksu.edu> <2382.2754d79e@waikato.ac.nz> <1990Nov29.025924.7662@maverick.ksu.ksu.edu>
Sender: news@midway.uchicago.edu (News Administrator)
Organization: Mathematics Department, University of Chicago
Lines: 49

In article <1990Nov29.025924.7662@maverick.ksu.ksu.edu> jxf@castor.cis.ksu.edu (Jerry Frain) writes:

>Yes!  All applications, your precious debugger included, should not be
>able modify the memory space of *other* programs.  You will note that
>this should not encompass the development-time debugging involved in
>creating programs (but, I am unfamiliar with the way that Mac debuggers
>are implemented).

How are you going to get around it? Either the debugger is locked out
or it isn't.


>Further, and more importantly, applications should not be able to write
>in OS memory space.

The fact is, though, that there are Mac apps that *do*.  Worse,
there are gazillions that depend on being able to *read* low RAM,
given that Apple describes low-memory globals in Inside Mac.  The
effort involved in converting them all would be enormous.  (And I'm
not sure I understand what's so terrible about it.  In a multiuser
environment, there are security questions; but, on a Mac, you can't
run into that.  Responsible access shouldn't break things too badly.)

>There is no excuse for not utilizing modern (and abundant!) memory
>protection hardware.
How about "most Macs don't have it"? Pluses, SEs, Classics, LCs, most IIs.

>Simple, basic, controls for protecting system integrity.  That's not too
>much to ask now, is it?  IBM will soon make OS/2 their standard.
>Preemptive multitasking, memory protection, etc.  With the advent of
>window systems that rival the Finder, coupled with the power of a
>command shell, Apple will be left out in the cold if it does not pick
>up on these very important concepts, soon.

Don't be so sure.  Most people aren't going to be affected by (let
alone understand) preemptive multitasking & memory protection.  Well-
written programs don't need such things; and most consumers just
use commerical software (am I wrong here? It is my impression, based
on what I see.), which (hopefully) is done right--at least right
enough not to break.

And all the window systems & command shells in the world can't beat
the fact that the IBM world is full of non-windowing programs that
don't even have a common Clipboard.

| Francis Stracke		| My opinions are my own.  I don't steal them.|
| Department of Mathematics	|=============================================|
| University of Chicago		| Until you stalk and overrun,	     	      |
| francis@zaphod.uchicago.edu	|  you can't devour anyone. -- Hobbes 	      |