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From: boyd@necisa.ho.necisa.oz.au (Boyd Roberts)
Newsgroups: comp.unix.questions
Subject: Re: why different swapping modes on executables?
Message-ID: <2044@necisa.ho.necisa.oz.au>
Date: 15 Mar 91 00:59:26 GMT
References: <1991Mar12.012401.557@nowhere.uucp> <1991Mar12.104352.23097@kithrup.COM> <573@adpplz.UUCP>
Organization: NEC Information Systems Australia Pty. Ltd.
Lines: 18

In article <573@adpplz.UUCP> martin@adpplz.UUCP (Martin Golding) writes:
>My impression is that the (original) version of the Magic Number was
>the actual value to load into the PDP 11 MMU control register, to select
>one or the other model.
>

The original 0407 magic number was the PDP-11 instruction to branch
over the a.out header of the executable.  Back then the a.out header
was loaded into core with the executable code and data.

The other magic numbers were just arbitrarily assigned as new a.out
formats evolved.  Chris or Doug or Henry will correct me if I'm wrong
on this point :-)


Boyd Roberts			boyd@necisa.ho.necisa.oz.au

``When the going gets wierd, the weird turn pro...''