they were really slow. It was fun to watch them do a division as there were no electronics; everything was done with gears and cams and shafts. There tended to be a lot of jumping around on the desk as the machine ground through the calculation. It turns out that bits move a lot faster than rotary motion .

My first full featured electronic calculator was bought in the early 70s and cost a few hundred $s. It was a Japanese Commodore US*4 which had a fluorescent readout and which I still have. It has a broken wire to the battery but I think if I took the time to fix it, it would still calculate! I needed a cheap one and last year bought on from Office Depot for around $5-6. It works fine!

The only ones that have held their value are the Curta calculators that the sports car enthusiasts used to run rallies. Some of those still sell for $1000+ and the rare ones in the thousands. I don't have one , but there was one shown on Pawn Stars a couple of years ago.

Let me know if anyone finds an adv chip with CURTA on it. There should be a crank coming out the side of the chip.