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From: uace0@uhnix2.UUCP
Newsgroups: comp.sys.atari.st
Subject: Re: RAM locations for safe use
Message-ID: <387@uhnix2.UUCP>
Date: Fri, 29-May-87 20:24:53 EDT
Article-I.D.: uhnix2.387
Posted: Fri May 29 20:24:53 1987
Date-Received: Thu, 4-Jun-87 05:02:16 EDT
References: <381@uhnix2.UUCP> <738@atari.UUCP>
Organization: University of Houston
Lines: 49

In article <738@atari.UUCP>, apratt@atari.UUCP (Allan Pratt) writes:
> in article <381@uhnix2.UUCP>, uace0@uhnix2.UUCP (Univ ATARI Comp
> Enthusiasts) says:
> > 
> > In response to Moshe Braner's questions concerning a safe place in
> > memory, I can only think of one location that is safe.  Actually, it is
> > a series of a few longwords that are only safe until the system crashes. 
> > That's right, the register save area used after a crash.  As far as I
> > know, these memory locations are only used on a system crash, so should
> > be free to use while the system is operating normally. 
> > 
> > - Mike
> 
> This turns out not to be the case.
> 
> In any case, the register save area of memory is overwritten by
> any bombs, not just the ones resulting in a total crash.  If you
> want a safe place in memory, use your own BSS and execute Ptermres()
> to leave your program.  If you want someplace that'll survive a reset,
> I can't think of a reliable one.

True, but consider this:

If the application you are running is communicating to another process, and it
dies (bombs out) can you consider that the info it writes is valid?  I would
think not.  If you are able to start the process up again, then it will write
over the bomb info and then the location works.  If the system does not crash,
(why should it :-)) then they will work, and remain untouched.  If something
bombs, I would think that the protocol is not working anyway, right?

I imagine it really depends on whether or not the communicating processes know
when the other is active.  And given that the person can write programs that do
not bomb, then I think the locations would work, without taking up any more ram.


The opinions expressed do not necessarily reflect those of Allan Pratt.
But then why should they?  :-)
I hate disclaimers... (I disclaim that)

- Mike Vederman


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