[Izkata]

Even those before git - what they're describing sounds a bit like RCS, the precursor to CVS, which came before SVN.

I've never used RCS or CVS myself, but I remember the file locking thing in descriptions of it, and that it was why CVS was named "concurrent" - it fixed that limitation.

[wolf550e]

VSS6 had file checkout, which IIRC locked the file preventing other devs from editing it. It was popular with Visual C++ 6.0, circa the year 2000.

https://en.wikipedia.org/wiki/Microsoft_Visual_SourceSafe