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From: dhp@ihlpa.UUCP (Douglas H. Price)
Newsgroups: comp.sys.intel,comp.lang.c
Subject: Re: segments and Unix
Message-ID: <2327@ihlpa.UUCP>
Date: Tue, 18-Nov-86 17:53:06 EST
Article-I.D.: ihlpa.2327
Posted: Tue Nov 18 17:53:06 1986
Date-Received: Wed, 19-Nov-86 02:46:54 EST
References: <13802@amdcad.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 19
Xref: mnetor comp.sys.intel:26 comp.lang.c:90

> Suppose every data structure were in its own segment. 
>
> Would this be worth doing? 

This is (if I understand correctly) exactly what happened in the object
oriented environment of the Intel 432 processor.  Each data (and code)
object could only be accessed in the appropriate context.  All objects not
explicitly referenced in the current execution context where turned off,
and would cause a detectable fault.  The problem with doing this on a
286, for instance is again the extreme overhead necessary to set up
(or check access permissions) on each data reference.  It is also not
a general solution on a 286; you can run out of segments too quickly.
It was the overhead (and the general confusion about how you programmed
object oriented hardware) that killed the 432 off. 
-- 
						Douglas H. Price
						Analysts International Corp.
						@ AT&T Bell Laboratories
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