Solver, HP Solve, etc.

[HP67]

Is the "Solver" the same thing as "HP Solve?"

Are there any good articles on the "Solver"? I have all the HP journals downloaded but I don't think I have an index so finding stuff is a little tricky. Is there a canonical description in HP calculator manuals, or is most of the stuff known from using it over the years?

I'm curious about things like how many versions of the "Solver" exist, what is the history behind it, and which HP calcs have it.