The Museum of HP Calculators

The Museum of HP Calculators displays and describes Hewlett-Packard calculators introduced from 1968 to 1986 plus a few interesting later models. There are also sections on calculating machines and slide rules as well as sections for buying and selling HP calculators, an HP timeline, collecting information and a software library.

  thanks to Coudal Partners

Not only does it cover HP calculators, but it has an excellent section on the amazing mechanical calculators like the Friden SRW. How it was done in the old days.