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Running CHIP-8 on an HP 48 calculator (2020) (tobiasvl.github.io)
49 points by hggh 13 days ago | hide | past | favorite | 21 comments





I really, really miss the HP48 series.

It's obsolete now, but it's the best calculator design in the history of calculator designs. I wish there was a modern version. The old ones are starting to break down, and many cost more today than they did new. Many common operations are very, very slow relative to modern models.

The TI calculators are horrible in comparison, and the HP Prime is a blunt kludge.

Key features I'd like:

- High-quality keys

- RPN

- Being able to handle units. Can't tell you how many times that's saved me from metaphorically blowing up a space shuttle.

- Very rapid use of variables. `<< 1/ SWAP 1/ + 1/ >> P A R STO` and 11 keystrokes later, I have a function defined for parallel resistors.

- Comprehensive equation libraries

- Ideally, some level of backwards-compatibility (even through an emulator kludge)

Key modernizations:

- A fast CPU

- A high-resolution color touch screen, with nice rendering of symbolic equations

- A more modern engine for symbolic manipulation

- Python (integrated with RPL, for the numeric libraries)

- Modern connectivity (802.11+USB-C+bluetooth, supporting data streaming, external keyboards / mice, acting as a keyboard / mouse, streaming to an external screen, etc)

- Open-source, and software packages (apt-get style, ideally, and app store style, possibly)

One thing I've considered doing -- if I ever had time -- was to make an HP48 keyboard for my desktop. I don't need the portability, and I wouldn't even mind if the software were running on my desktop.


> A fast CPU

The HP50g which I guess qualifies as part of the HP48 series did replace the Saturn with a Samsung ARM920T based SOC which was relatively screaming.

I have both the 48GX and the 50g and did end up gravitating to the 50g even though it doesn’t quite have the same level of build quality, it isn’t a piece of shit either. I also smashed the LCD on it, again much harder to do with the 48 though the contrast in the latter was pretty bad.


Erable was a damn advanced and flexible CAS that chewed up most vector calculus and differential calculus problems.

Huh. That took me down a rabbit hole. I wasn't aware this was released as open-source. That solves a few unrelated problems for me.

Expanding on the above post:

Erable was replaced with Xcas / giac, which is the more advanced CAS used on the HP Prime. Almost all of this is open-source (with the exception of small bits of Erable developed by HP, not needed for Xcas /giac), under a mixture of LGPL and GPL3 licenses (mostly the latter).

This gives a surprisingly advanced and complete symbolic algebra system for use in your own programs. Although developed in C/C++, it has interfaces to many languages, including oddly enough, JavaScript. In that case, the C/C++ is compiled to WebAssembly with enscripten. But of course, more common ones like Python or LaTeX exist too.

It is used in many systems, including Geogebra.

It is developed in France, and feels, for a lack of a better word, French. I have the odd experience of having seen SWE culture in several countries, and this is firmly in the French camp. I suspect if it were more American, it would be better-known given the level of completeness and quality.


Why are you giving me a ChatGPT-like wikipedia summary?

I used it to actually do shit like ace the SAT-I.


I loved my HP48GX, no other calculator ever came close. It's been in the drawer for decades now, I guess I should sell it to someone who will use it... Need to look into that. I didn't think there is no replacement for it, still.

SwissMicros is making very HP-like RPN calculators https://www.swissmicros.com/products But nothing that could compare to the 48 series, yet

The iHP48 app on iOS is very good.

It’s not the same as an original due to the lack of real keys, and, frankly, I don’t think the phone holds as well as the original calculator. Phone also feels heavier.

However, having the backlight is a vast improvement. I’d enjoy the original with a backlight. My modern eyes just can’t read the original screen well any more.

Mind the other benefit of the app is simple ubiquity being part of the phone. All reasonable trade offs.

But I can’t see using the phone for extended work compared to the original. The overall ergonomics just aren’t there.


If I could use my Android screen with a dedicated keyboard, that might be a compromise. A keyboard is maybe a week's worth of work, all-in (PCB design, installing firmware, etc). I'm not sure how much software work it would be to make it happy with an emulator -- probably much more.

I really wish the HP48 software were released as open-source. It'd be a huge good will gesture right now. Right now, this whole ecosystem is quasilegal. iHP48 is one DMCA takedown notice from ceasing to exist. With that uncertainty, it's not a place I want to devote my time.

In 2024, I'd really like to have crisp fonts, more than 4 items in my stack, and ideally, touch for the menus, and simple upgrades like that. I think that would, practically, require source code rather than just emulation.


CHIP-8 was what caused me to stop using github and host my projects privately. I had no license set and had everything marked as copyright and it still ended up on being ported to the Nintendo Switch without my permission. I deleted the repo thinking that would be the end of it but it gets worse. When I type my uniquely spelled name with co-pilot enabled it starts auto completing my full name and code. :(

Tbh All of that seems cool to me: my chip8 emulator, of all things, compelling people to port it to the Switch, and showing up in LLM.

Different strokes.


The HP 48 was an absolute joy to use. It’s a shame that TI dominated the educational market.

I still use an HP 48GX for all my university courses that require a calculator (not many nowadays, the best math courses are the ones without numbers in them). I bought it used in 2020 and it's been one of my favorite sub $25 purchases I've ever made!

HP 48s were forbidden at my school because they could do some symbolic stuff, like derivation etc.

I had one anyway


Could also solve quadratic equations. Also could work with imaginary numbers ( j notation) used in electrical engineering problems

Yep! I had an HP 48 (48SX, I think) in high school. Everyone else had TIs.

My 1st computer (45 years ago) was the "Dream 6800" and it had a CHIP-8 interpreter in a 2 KB EPROM. It was DIY construction published in Electronics Australia in 1979 Link has lots info about the computer , including from original designer https://www.google.com/search?q=Michael+Bauer+Dream+6800

If you're not aware, there is a Dream 6800 emulator https://github.com/tobiasvl/drom

This is actually how I discovered CHIP-8. Yes, I know it dates back to the 1970s, but it was the version on the HP48 in the 1990s that introduced me to it.

Saturn RPN gang, represent! ;)

Oh the memories of joys of turning on and off the physics lecture hall TVs from 20m/60' away.

And the RAM upgrade hacks.

Recently, I bought an interesting accessory, an LCD overhead projector for the HP 48.


I still use my HP 48G+ near daily. My favorite calculator of all time, by far.



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