Terminated: 1977
Where it not for its LED display and volatile memory this calculator would still stand a good chance today (2001). It has (almost) everything one needs.
It’s almost magical. Or am I getting carried away? Remember the early seventies? Before the personal computer, HP created a beautiful programmable hand held device. Some people claim it all started with the TI-59, but I’m certain that they are wrong. This is the one that started it all.
Because the calculator’s memory is volatile, this calculator contains a card reader/writer. All kinds of programs were available on little magnetic memory cards (one is visible on the picture, half sticking out), and user programs could be stored on write enable cards.
Of course this calculator has its drawbacks. Editing a program is a pain, there are three shift keys and it’s power hungry (although not extremely so).
And what I admire so much in the older HP calculators is their robustness, today (2023) the card reader still works perfectly. All keys operate flawlessly, the only thing that has died is the battery pack.
For more information on this beauty please refer to the better sources, like The Museum of HP Calculators (link validated 2024-01-13). There’s simply too much to tell about this one.
There’s also some information on the HP 65 on HP’s official website (link validated 2024-01-13).
The Hewlett-Packard Company Archives site also has some information on this calculator, see A Superstar Product: The HP 65 Calculator (link validated 2024-01-13).
Its successor (much later on, in 1976) is the HP 67.
Thanks Jos van Eindhoven and Arij Dekker for their contributions.