Re: more addressing, Why I've Dropped In

According to Stephen Fuld  <sfuld@alumni.cmu.edu.invalid>:

On the System/360, a FORTRAN compiler typically compiled each subroutine

in a program separately from every other subroutine. They just got
linked together by the linking loader in order to run.

>
I'm not sure what you mean by "linkingloader"  The linkage editor (IIRC
IEWL) linked together all of the object modules created by the compiler.
 Loading the program was a different operation, again IIRC, done by the
initiator in each partition)

OS and its descendants have both a linkage editor that combined a bunch of object
modules and wrote a load module on disk, and a loader that leaves the result in
memory and runs it directly.

The loader is not the same as program fetch, the part of the operating system
that reads and starts a load module.  Load modules (and object decks) notionally
start at location zero, and have a relocation directory that lists all of the
places there are address pointers that need to be adjusted to the actual location
where it's loaded.  That relocation was quite simple; the overlay loader did it
too and I believe was under 1000 bytes.

For people who want more details, I shamelessly recommend this book:

https://shop.elsevier.com/books/linkers-and-loaders/levine/978-0-08-051031-6

--
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
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