According to Stephen Fuld <[email protected]d>:

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, [email protected], Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly

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On 6/18/2025 11:19 AM, John Levine wrote:

According to Stephen Fuld <[email protected]d>:

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.

Thanks John. I didn't know that as I only used the linkage editor.

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

WOW!!! A twenty five year old book on a somewhat obscure topic is
apparently still in print. Congratulations!


--
- Stephen Fuld
(e-mail address disguised to prevent spam)

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Stephen Fuld <[email protected]d> schrieb:

On 6/18/2025 11:19 AM, John Levine wrote:

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

WOW!!! A twenty five year old book on a somewhat obscure topic is
apparently still in print. Congratulations!

I bought it :-)

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On 6/18/2025 11:13 PM, Thomas Koenig wrote:

Stephen Fuld <[email protected]d> schrieb:

On 6/18/2025 11:19 AM, John Levine wrote:

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

WOW!!! A twenty five year old book on a somewhat obscure topic is
apparently still in print. Congratulations!

I bought it :-)

Recently or some time ago? Perhaps you should write a review and earn
John some royalty bucks! :-)


--
- Stephen Fuld
(e-mail address disguised to prevent spam)

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Stephen Fuld <[email protected]d> schrieb:

On 6/18/2025 11:13 PM, Thomas Koenig wrote:

Stephen Fuld <[email protected]d> schrieb:

On 6/18/2025 11:19 AM, John Levine wrote:

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

WOW!!! A twenty five year old book on a somewhat obscure topic is
apparently still in print. Congratulations!

I bought it :-)

Recently or some time ago?

Ordered on 2023-03-27, so that may be considered "recently"
or "some time ago", depending on your definition of the word.

Perhaps you should write a review and earn
John some royalty bucks! :-)

It certainly helped me understand the concepts (especially relocs)
when trying to get to grips with the concepts for the My 66000
assembler. Thanks, John :)

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