In my opinion, the HP-27 was the best pocket calculator of its day -- perhaps
the best of all time. It could do algebraic, statistical, and financial
routines -- all hard wired. Yes, it had a LED display, and needed to be
recharged often, but it could do it all. Mine won't any more, because the key
contacts have been worn out. I would pay dearly for the same capabilities in a
similar wonder machine with LCD display.