Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!aplcen!samsung!caesar.cs.montana.edu!ogicse!blake!Tomobiki-Cho!mrc
From: mrc@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin)
Newsgroups: comp.arch
Subject: Re: ABI and growth
Message-ID: <5344@blake.acs.washington.edu>
Date: 16 Jan 90 19:47:17 GMT
References: <6186@celit.fps.com> <2020@crdos1.crd.ge.COM> <6197@internal.Apple.COM>
Sender: news@blake.acs.washington.edu
Organization: Mendou Zaibatsu, Tomobiki-Cho, Butsumetsu-Shi
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In article <6197@internal.Apple.COM> desnoyer@apple.com (Peter Desnoyers) writes:
>This sounds like a variation on run-time loading. I'm not sure of the 
>specifics, but I believe some variation on {link in call to loader, load 
>function on first call, patch stub to jump to loaded function} is used in 
>[...] TOPS-20.

Not that I know of, and I was a TOPS-20 OS programmer for 10 years.
It was possible for user programs to do something like this, and I
think the FORTRAN overlay system (used mostly on the older TOPS-10
operating system) did, but it was not at all general practice.
TOPS-20 is a demand-paged virtual memory operating system.  Usually
your program would have everything lunk in with it, or call a
well-defined library segment (usually a TOPS-10 style "high segment")
that would be separately loaded.  "Loading" an executable program (as
opposed to linking relocatable binaries) merely involved setting the
swap pointers for the appropriate process page(s) to that particular
file on the disk; this made sharing of pure pages easily (and in fact
impossible to avoid).
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