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From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.unix.questions
Subject: Re: why different swapping modes on executables?
Message-ID: <15473@smoke.brl.mil>
Date: 14 Mar 91 21:07:06 GMT
References: <1991Mar12.012401.557@nowhere.uucp> <1991Mar12.104352.23097@kithrup.COM> <573@adpplz.UUCP>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 10

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.

No, not at all.

The original a.out magic number was a PDP-11 branch-always instruction
that jumped around the a.out header, so an a.out could be executed
directly, as in a boot block or standalone diagnostic program.