David T. Lewis wrote on Mon, 11 Jan 2021 20:04:32 -0500
> The SVN repository history is on line, and begins October 2001:
> 
>   http://squeakvm.org/cgi-bin/viewvc.cgi/squeak/trunk/platforms/Cross/vm/sqVirtualMachine.h?revision=2&view=markup

The VM was originally found in the .sources and .changes files, so
looking at the #initializeBytecodeTable method I can see that the only
change was that Squeak 1.1, 1.16 and 1.18 had

         (138 143 unknownBytecode)

and that got replaced in Squeak 1.22 by

        (138 143 experimentalBytecode)

There were no more changes until at least Squeak 3.8. Eventually the
code was moved to VMMaker.

For the history of named primitives and similar things I would first
look into the code in the compiler that parses the methods.

-- Jecel