The HP65 was an amazing calculator. It did all of the things other calculators did, and then did more. It was also the world’s first programmable calculator. You’d do the steps to work something out, the first time, and then it remembered them all and repeated the process for other values. Brilliant.

I never thought I’d get my hands on one of these.

I loved the Hewlett-Packard developed calculators so I did get the HP65’s successor, the HP67, but I came in just a few months too late to have a HP65.

The ’65 had 100 program steps and 9 memories. It had programmable keys – you type in a program for the “A” button and then pressing “A” always did that program. Likewise for “B” and so on to “E”. That’s five programmable keys.

It also had a magnetic card reader (and writer) so that you could save and reload programs later. People had whole packs of cards in their pockets. No matter the problem, you could load a card and solve it. Just brilliant.

I had always thought I’d write an emulator for the HP65 so I could have a play with it. It’s a lot of work but a worthwhile cause. For years the amount of work (and lack of experience with or a manual for) the HP65 got in the way. However, I recently stumbled across a microcode-based emulator. This runs the same internal instructions as the real thing so it does exactly what the real thing does.

The emulator had a few short-comings from my perspective so, having been inspired again, I rewrote it to be IMHO a little more useful and life-like. I’ve added a “card reader” interface so you can save and reload programs. It’s also easier to know what the additional function keys do. There’s more actions available if you tap the emulator screen. I think you’ll like the result.

You can: use it, install it (HTML5) or buy a copy to keep ($5 USD).

There is also Help for the HP65 Emulator.

handheld computing