Magnetic cards appeared in later HP calculators - starting with the HP-65 - and were copied by TI. These calculators look a bit clunky and retro today compared

Magnetic cards appeared in later HP calculators - starting with the HP-65 - and were copied by TI. These calculators look a bit clunky and retro today compared to modern phones, but they were unbelievably futuristic in the mid-70s. The idea that you could have a programmable microcomputer in your pocket which could load applications from plastic cards was jaw-dropping.