Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!pyrdc!grebyn!ckp
From: ckp@grebyn.com (Checkpoint Technologies)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Amiga Resource tracking & protection.
Message-ID: <19479@grebyn.com>
Date: 19 Mar 90 22:48:04 GMT
References: <235.260236d8@waikato.ac.nz>
Reply-To: ckp@grebyn.UUCP (Checkpoint Technologies)
Organization: Grebyn Timesharing, Vienna, VA, USA
Lines: 23

In article <235.260236d8@waikato.ac.nz> hamish@waikato.ac.nz writes:
>
>I keep reading about people saying that programs should be specially written 
>to cope with memory protection. Memory protection is a function of the OS, not
>the individual programs. To make it easy to run those programs that would
>break, then it should be able to be turned on & off, maybe on an individual
>basis per program. (ie the OS detecting a bounds fault & getting the data
>or writing the data).

	Well, the problem is that Amiga programs are mostly written with
the knowledge that there is no memory protection.  So in a sense all
Amiga programs are already concerned with memory protection, actually
the lack thereof.  So when you first make one task's address unreachable
by another, that program will crash becayse it had always assumed that
it was addressable.

	In other protected memory systems, the applications are all
aware of the memory protection.  They must specifically ask for an area
of memory to be shared between two or more processes in some way, either
by distinguishing between lightweight threads and heavyweight processes,
or by creating named shared memory sections, or by opening pipes or
message queues of some sort. It's all very formal.  In the Amiga, it's
all very casual.