[anonymousiam]

Back in the late 70's, I made a rotary phone dialer for my HP41C calculator. I connected a NC reed relay to the piezoelectric beeper and put the NC contacts in-line with my telephone line. I used "synthetic programming" (undocumented opcodes) to get the short duration beeps needed for the dialing pulses. I could enter a name (alphanumeric!) and it would look up and dial the phone number.

About 10 years ago, I met a guy named Keith Jarrett at my company. As I was about to ask him if he was the Keith Jarrett who wrote a HP-41C Synthetic Programming Manual, he interrupted me and said, "No, I'm not the musician. Everybody asks me that." So I finished my question and he was very happy and surprised, because he was the author of the book I had read 35 years prior.

https://picclick.com/HP-41-Synthetic-Programming-Made-Easy-b...

https://www.hpmuseum.org/prog/synth41.htm

[johnea]

A friend and I also made this!

We used it as a speed dialer that worked on any phone.

I still have the hard copy of the synthetic programming guide!

Even outside of that technique, the calculator was a very powerful programmable tool for the early 1980s.

The same friend and I also wrote a program for performing all of the calculations for a grad class in S-parameter modeling of RF transmission. We were so proud, we showed off the program to our professor. Our "reward" was having calculator "programs" banned during all tests 8-/

We didn't realize until later, that there was a "turf war" going on between the RF section of our EE department, and the digital electronic section.

This is how the HP-41CX calculator helped me learn one of the most significant lessons of my EE degree: when it comes to human decision making, the tech is often far from the top priority.

[anonymousiam]

Great stories. I had a similar experience with one of my college math professors (I was 16). I showed her that my calculator (with the Math module) could transform a 9th order matrix in a few seconds. She shrugged, because she knew that I didn't need the calculator to ace her tests.

The dialer was one of only two mods that I had made to my 41. I brought out the piezoelectric wires via a two-pin female .1" "berg" connector that I had added to the lower right side of the case. (I wish I had a photo.) The other mod used similar hardware; I put a magnetic reed switch inside, which changed a capacitor value for the system clock when a small magnet was attached (via Velcro) to the side of the calculator. The result was that my 41 would run its programs twice as fast. I had to remove the magnet to use my auto-dialer, because otherwise the timing was wrong. In my area, GTE didn't switch to ESS for another 10 years. Oh the fun!

[jtwaleson]

Cool story :) out of curiosity, do you program those kind of things on the calculator itself? I did that with the hp49g and was proud of the programs I was able to write in such a constrained environment, but the single line display of the 41c would be a real achievement!

[anonymousiam]

Thanks for asking. Yes, the calculator itself was the first "computer" that I owned, and there was nothing else to connect it to, or to emulate it with. (I had my own PDP-11 at work, and I had previously done batch-mode programming on an IBM 370.) I bought my 41C in 1979 (made in the US!), and spent several thousand dollars on peripherals over a period of about three years. It was a big investment in a platform that did not interoperate with anything else, and I ended up giving it all away. I didn't keep any of it, including all the programs I had written and stored on magnetic cards (a fine example of extinct storage media).

I may still have a spiral notebook, in which I did all of the code development. It would be a hard-copy of all the code I wrote. If I do still have it, I have no idea where it is. It sort of reminds me of the end of Citizen Kane.

Later on, I also got rid of my Synertek SYM-1 and all my CP/M platforms, except for one IMSAI 8080 S-100 box, which I eventually gave away to someone else. I didn't realize at the time (nearly 30 years ago) that the IMSAI 8080 was quite collectable, and was going for about $800 on eBay. Still, I didn't regret it much.

The old systems evoke a sympathetic nostalgia, but actually using them is an exercise in patience, and eventually evokes a desire for more modern systems.

I've still got some emulated retro hardware and some old software emulators, but I don't really use them much.

[johnea]

To this day, I still use a linux desktop simulator for the HP-41CX calculator!

The original website seems now offline:

https://nonpareil.brouhaha.com/

But the code is still available:

https://github.com/brouhaha/nonpareil

[anonymousiam]

I took a look at nonpareil, and decided to give it a try. There were a few dependencies that weren't listed, and I had to change wasm.h to wasm_y.h in three files, then it wouldn't build on an nfs mounted filesystem because it was trying to run an executable (str2png). Eventually I got it installed and working. Very cool!

[anonymousiam]

I use the "realcalc" Android app. I first purchased it for PalmOS sometime around 1999. It's an absolutely fantastic emulator. I use Free42 on my iPad.

For the desktop, bc works fine for me.