The original Marc Rochchild/John Mashey and team code from PWB 1.0 can be found:  http://tuhs.org/Archive/Distributions/USDL/spencer_pwb.tar.gz
In the directory: sys/source/sccs4
The man pages are in the same archive but mixed with the rest of the commands in usr/man/man*

That said, there is Gnu version of same written C++ if IIRC: https://www.gnu.org/software/cssc/

And there's more ... but I'll Larry offer details here other than point out his: http://www.bitmover.com/bitsccs/ [which is of BitKeeper] is a more modern implementation still]

On Fri, Jun 10, 2022 at 2:48 AM Ed Bradford <egbegb2@gmail.com> wrote:
Hi Warren,

Thank you for the amazing Unix documetation.
Do you know if there is a source code for SCCS anywhere on the net?

Ed Bradford

On Sun, Jun 5, 2022 at 8:40 PM Warren Toomey via TUHS <tuhs@tuhs.org> wrote:
Hi all, we have a new addition to the Unix Archive at:
https://www.tuhs.org/Archive/Documentation/Manuals/Unix_4.0/

This is the documentation for Unix 4.0 which preceded System V. The
documents were provided by Arnold Robbins and scanned in by Matt Gilmore.

Cheers, Warren


--
Advice is judged by results, not by intentions.
  Cicero