Newsgroups: comp.sys.amiga.hardware
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!jdickson
From: jdickson@jato.jpl.nasa.gov (Jeff Dickson)
Subject: Re: Amiga Custom Chips - Mem management and resource tracking
Message-ID: <1991Apr3.230854.17091@jato.jpl.nasa.gov>
Reply-To: jdickson@jato.Jpl.Nasa.Gov (Jeff Dickson)
Organization: Jet Propulsion Laboratory, Pasadena, CA
References: <CPETTERB.91Apr2105151@mickey.glacier.sim.es.com> <1991Apr2.235710.13984@news.iastate.edu> <1991Apr3.201259.8377@engin.umich.edu> <1991Apr3.153236.1@vf.jsc.nasa.gov>
Date: Wed, 3 Apr 91 23:08:54 GMT

In article <1991Apr3.153236.1@vf.jsc.nasa.gov> kent@vf.jsc.nasa.gov writes:
>> 
>>   What is the big deal about memory protection and resource tracking?
>> Sure, it might be a nice toy, but it wouldn't be real useful on a
>> single-user system.  Is this one of those things people want just
>> because Unix has it?
>> 
>> 
>
>Memory protection would prevent a program crash from crashing the whole
>machine.  The memory management unit would limit each program to its own memory
>space.  Thus, the program could not go stomping off into memory with muddy
>boots.  Hence the end of the Guru.
>
	Memory protection would not be the end of the GURU. I speak from
experience. There are other types of errors which can be induced without
memory violations.

>Resource tracking would allow the operating system to deallocate all resources
>a program failed do because it crashed or the programmer did not write code to
>deallocate all memory, devices and so on.
>
	Resource tracking is a neat feature, but it would entail greater
memory consumption and eat up more cycles. Not closing files or deallocating
memory, doesn't cause an immediate system failure. Stomping off into memory
with muddy boots does. I think memory protection is more important.

		-jeff


>
>--
>
>Mike Kent -  	Lockheed Engineering and Sciences Company at NASA JSC
>		2400 NASA RD One, Houston, TX 77058 (713) 483-3791


