HP 45 (and 35 and 80) Calculator Emulator | Hacker News Reader

HP 45 (and 35 and 80) Calculator Emulator

sarahkmarr.com

95 pointslinsomniac15 comments

I find these calculators fascinating. I'm not a computer scientist, but I find it really intriguing that their processors naturally handled binary encoded decimal, and also their algorithms for calculating trig and log functions on such limited processing power. I understand the early HPs excelled themselves on returning accurate results, often more accurate than more modern machines.

Day to day I use free42/plus42 on my phone for working out quick calculations. I find the RPN works best when you're trying to solve numerical questions as you go. It also has great time/date functions which help me to plan driving trips etc, and it is programmable, so I have a few useful calculators on it for EV charging etc.

A series of articles in the HP Journal explained how these algorithms worked:

May 1977 - Square Roots (pg. 22): https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1977-05.pdf

June 1977 - Trigonometric Functions (pg. 17): https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1977-06.pdf

November 1977 - Inverse Trigonometric Functions (pg. 22): https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1977-11.pdf

April 1978 - Logarithmic Functions (pg. 29): https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1978-04.pdf

Beautiful resources. Thank you!

I still use a descendent, the HP 50g for a lot of stuff. I've got programs I use regularly that are 30 years old now!

Would love to know what old programs you still use regularly do.

Mostly statistics operations on simple lists, a decision analysis tool and financial planning.

The 50g remains the best calculator I've ever used. I've also got a prime, and while it may be faster and come with a larger library, it feels so much more limited and clunky.

Many emulators for these old calculators go out of their way to be as skeuomorphic as possible, using JPEGs of the actual calculator hardware. While some people may enjoy that, I appreciate that these emulators don't make the effort. My dream has always been a 50g emulator in this style.

The skeuomorphism comes in handy sometimes: the 50g emulator on my current smartphone reproduces the keyboard at ~94% scale, which is close enough that muscle memory transfers over. But for use on a desktop computer, I agree that the skeuomorphism is not necessary.

Beautiful. I'm glad the art of calculators isn't entirely lost and that people still appreciate how well designed these machines were.

As a kind of "me too", I'll shamelessly plug my own pet project, which shows how much I value a device that is older than me: https://partsbox.com/blog/wireless-charging-for-a-hp-25-calc...

People definitely still appreciate HP calculators. Just this summer, the HP-15C has been re-released as a collectors edition.

https://www.hpmuseum.org/forum/thread-19886.html

Beautiful and fascinating, and many other projects on her retrocomputing page. And the UI uses Tk (via Tkinter): heart_emoji.

> It not only runs (included) ROM code from the HP-45, but also the HP-35 and the HP-80

I thought that ROM code is copyrighted and cannot be redistributed without permission. Maybe they got that permission from HP. The TI calculator emulators require a separate ROM dump from an actual physical calculator.

https://nonpareil.brouhaha.com/microcode_copyright_status/

For some older HP calculators, the ROM code was disclosed in patents.

Over the top is underrated. :)

Reply on news.ycombinator.com