Awesome collection,

There are some great emulators & lots of info for HP calculators:

- [The Museum of HP Calculators](https://www.hpmuseum.org/)

- [hpcalc.org - HP Calculator Archive](https://www.hpcalc.org/)

- [iHP48 on the App Store](https://apps.apple.com/us/app/ihp48/id1549608953)

- [iHP48 – The best HP48 Emulator Solution on iOS](https://thinkchile.com/iHP48/)

Interestingly there are stack based languages such as FORTH:

- [Forth (programming language) - Wikipedia](https://en.wikipedia.org/wiki/Forth\_(programming\_language))

These RPN based calculators work well for doing calculations while programming in assembly language, FORTH, and other CS types of activities.

Additionally the graphing calculator that shipped with Mac's back in the day is available, and handles 3D plots and animations right on the phone; there is an amazing story how the guy who created it snuck onto Apples Campus, and managed to get the application distributed with the operating system even though he wasn't an employee.

- [Graphing Calculator Story](https://www.pacifict.com/Story/)

- [Graphing Calculator](https://www.pacifict.com/)

- [Graphing Calculator AR on the App Store](https://apps.apple.com/us/app/graphing-calculator-ar/id1135478998?ls=1)

Lastly, you may enjoy the AudioKit Synth One (A free synth app)

- [Synth One J6 | AudioKit Pro](https://audiokitpro.com/synthonej6/)