The HP 9100B Calculator is the 2nd calculator built by HP. It dates from 1969. What is incredible about this calculator was its complexity. Using discrete components (no IC’s) it not only ran as a calculator, and ran very well, but it contained core memory, rope ROM, had its own CRT monitor and was essentially a mini computer. To use this calculator to its full extent, you use programming cards to store results and preform functions. It was the Rolls-Royce of calculators.

It came at a small price though. According to Wikipedia that price was and eye-watering $5000 in 1968 for the 9100A model, or $36,000 (£28,000) in 2018 money.


Jeff Quitney’s Youtube channel has a restored video of how the 9100 calculator works: