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From: dant@ryptyde.UUCP (Daniel Tracy)
Newsgroups: comp.sys.mac.system
Subject: Re: No cmd-opt-e in system 7?? (answer)
Message-ID: <97@ryptyde.UUCP>
Date: 23 Jun 91 03:30:33 GMT
Article-I.D.: ryptyde.97
References: <1991Jun20.232314.4961@m.cs.uiuc.edu> <1991Jun21.171557.25085@MDI.COM>
Reply-To: dant@ryptyde.UUCP (Daniel Tracy)
Organization: Ryptyde Timesharing (ryptyde.cts.com)
Lines: 32

Responding to the following:

"How would this help? The Mac would try to load the chooser into the
system heap, discover it needs more room, try to expand it, only to find
there wasn't enough memory, then give you an "out of memory" dialog.
You would be left in the exact same situation you are in now. At least
you have a chance of running the DA if you have VM going (if you can
run it...). As I understand it, the system heap never gets swapped,
so it still would have memory problems after loading the DA into the
system.
 
This brings up another question. Is it possible to lock out a running
application that has been swapped out? Consider this scenerio: Some
piece of  code is loaded into the system heap. It causes a large
application to be swapped. The new code is locked, and increases the
system heap so that the application no longer has enough memory available
to run. Possible? Or will the system catch it and keep the additional
code from loading into the system?"

1)  I thought the System 7.0 Process Manager treats DA's as applications 
for the most part. That is, they're given their own chunk of memory and
layer as applications are. Why would the Chooser be loaded into the System
Heap?

2)  With Virtual Memory, I don't think the above applies. Does the entire
application have to be loaded at once? I thought the Mac used demand-paged
virtual memory. That is, because of resources, only the parts that are
needed at the time are loaded into memory. Even if this weren't true, your
statement just doesn't seem right. Maybe I don't know enough about Mac OS,
but consider this:  You have 5 megs of VM total. As long as the CODE 
resource fits in this virtual space any amount of swapping can be done,
right? Am I taking your example wrong?