The HP-65 was not only HP’s first programmable scientific, but it could also read and write magnetic cards. There were several 'pac’s of cards allowing it to tackle financial, astronomical, aviation, electrical and other speciality field calculations. The buttons were double shot and have a lovely tactile click. The red LED screen is remarkably crisp and easy to read.
I’ll have to see if there’s a deep dive on that somewhere. It sounds fascinating!
I actually had the TI-59. I remember I entered a program where you are trying to avoid a missile running on vectors and a mine that was teleporting around on a Cartesian grid, and saved that on one of the magnetic strips. And also programmed the quadratic equation on a magnetic card. It had a base it could attach to that provided power and had a thermal printer strip. That calculator also had a place to put a pre-programmed chip into it. I think I had casino games or something.
If you’re wondering how I had all that in high school, well that was what my dad thought would buy my affection when he left my mom for the secretary… Didn’t work, but I got a piece of cutting edge hardware for it.