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.
When I graduated from high school I used the money I got in graduation gifts to purchase an HP41CV.
It was an amazing calculator. I wish I knew where it was!