It would seem that a Spinellis-like exercise for SCCS is possible:

PWB1.0 (1978): https://www.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/sccs4
SysIII (1980): https://www.tuhs.org/cgi-bin/utree.pl?file=SysIII/usr/src/cmd/sccs
SysVr1 (1983): https://www.tuhs.org/cgi-bin/utree.pl?file=pdp11v/usr/src/cmd/sccs
SysVr2 (1984): https://github.com/ryanwoodsmall/oldsysv/tree/master/sysvr2-vax/src/cmd/sccs
SysVr3 (1987): https://github.com/ryanwoodsmall/oldsysv/tree/master/sysvr3/301/usr/src/cmd/sccs
SysVr4 (1988): https://github.com/ryanwoodsmall/oldsysv/tree/master/sysvr4/svr4/cmd/sccs
Ultrix3.1 (1988): https://www.tuhs.org/cgi-bin/utree.pl?file=Ultrix-3.1/src/cmd/sccs

I did not find SCCS sources included with the BSD sources on TUHS, but there is a front-end “sccs” command. For sure, SCCS was used for BSD development. Kirk McKusick’s DVD has a directory "CSRG/historic1/sccscmds”, but I did not look into this further.

From here the trail probably continues with Solaris, GNU and Bitmover -- all very much outside my timeframe of research.

Paul

> 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]