I don't know enough about MVS but it too is public domain until 3.8j or so, and I would expect that the way you serviced the system was about the same: patch the assembly code from PTFs (or whatever those are called in MVS-land), reassemble the modules, relink into a kernel/system image/whatever the os-appropriate nomenclature is.

Adam

On Tue, Nov 10, 2020 at 5:10 PM Adam Thornton <athornton@gmail.com> wrote:
Pretty sure this VM/370 reference has, somewhere in its rather formidable bulk, what you're looking for.  Start around p. 225:

http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/370/VM_370/Release_6/GC20-1801-10_VM370_Sysgen_Rel_6_Jan80.pdf

Now granted VM was never the most popular of the IBM OSes.  But it was delivered (and patched) as assembler sources.  You may also enjoy Melinda Varian's "What Mother Never Told You about VM Service."  http://www.leeandmelindavarian.com/Melinda/tutorial.pdf

On Tue, Nov 10, 2020 at 5:06 PM Greg 'groggy' Lehey <grog@lemis.com> wrote:
On Tuesday, 10 November 2020 at 18:45:15 -0500, Clem Cole wrote:
> On Tue, Nov 10, 2020 at 6:11 PM Greg 'groggy' Lehey <grog@lemis.com> wrote:
>
>> I'm currently reviewing a paper about Unix and Linux, and I made the
>> comment that in the olden days the normal way to build an OS image for
>> a big computer was from source.  Now I've been asked for a reference,
>> and I can't find one!  Can anybody help?
>
> Mumble -- For IBM and DEC in the 60s and early 70s, the manufactures
> distributed the (assembler) sources to the OS and we could (and did)
> build from source but usually just built parts.

Right, this is my recollection.

> Remember, the target was the manufacturers HW so they were not
> giving away much.

Again, my assessment.

The real issue is: where can I find a reference?  Google brings up so
many false positives that it's not worth the trouble, and Wikipedia's
pages on "System generation" are too vague.

Greg
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