Comment by skissane

I played with SCCS on RSX-11M in the 1980s. SCCS is not a client-server architecture that allows you to share file history across the internet. It allows you to keep change history locally with your local source files. If you don't keep viable backups of your local files offline and offsite, it's going to be easy to lose even if your local files contain the entire history of your changes. It was only when we moved to DOS that SCCS became useful, since you could back up and share code using floppies.

When I worked on RSX-11M, and later VMS, we did not rely on SCCS because it had no added value. We relied on the file versioning provided by the file system and rarely kept more than one old version around because disk space was always at a premium. Changes to production code required filling out a paper form and passing it to the test department, who would submit the appropriate batch job to rebuild everything, then copy your changed files into the production directories after the tests pass. It was just like modern CI systems, except for the fact that it was mostly manual and a build-and-test cycle was at least 2 days.

Quoting the 1975 paper: "There are two implementations of SCCS: one for the IBM 370 under the OS and one for the PDP 11 under UNIX."

The original version was for OS/MVT and implemented in SNOBOL4 using the SPITBOL compiler. https://apps.dtic.mil/sti/pdfs/ADA084326.pdf says that SNOBOL4 was available for the RSX-11D by 1979.

I have no clue what Ericcson was using. My inference from the literature is that apparently when software developers have access to a version control system, they used it, even back in the 1970s.

FWIW, I regard versioned file systems as a form of version control.