Free42: An HP-42S Calculator Simulator (2005) | Hacker News Reader

Free42: An HP-42S Calculator Simulator (2005)

github.com

50 points_83te29 comments

SwissMicros make nice clones of classic HP calculators. They sell an HP-42s clone which runs Free42:

https://www.swissmicros.com/dm42.php

It’s a beautiful machine, superb build quality, as good as genuine HP pre-Fiorina. If anyone is considering one, you will not be disappointed.

I bought the DM15L only a couple of months before the 42 was released and it's built really well.

I don't have the HP to compare the button feel to so it may not be exact (and there are differences in looks) but it's nicer than any other calculator I've seen available to buy today.

There’s less travel in the Swissmicros keyswitches, that’s the main difference. But it’s still massively more tactile than a touchscreen.

Another +1 for the DM42 here. It's a great calculator and very nicely built.

It uses a transflexive memory LCD display, kind of similar to eink, which is a pretty good match to the application, batteries last forever, and the software is very good.

It compares very favorably to the HP-35s (and the WP34s) I was using prior to it.

EEVBlog review:

https://youtu.be/Ong91Ji3iDk

And they use free42 under the hood :).

I’ve been using the iOS version for longer than I remember. It lets me leave my actual 42S at home where it’s safe and sound...

https://apps.apple.com/us/app/free42/id337692629

There's also an Android version:

https://play.google.com/store/apps/details?id=com.thomasokke...

I still have my HP48G I bought in 2000 for college calculus. Introduced me to reverse polish notation, loved the tactile feedback from the keys. I bought a simulator for it on my phone.

Lately got my HP48s stolen when our office was raided by burglars. Had not used it for quite a while but loathing losing the university studying memories attached to it.

Why (2005)?

The tool on github (and the homesite):

https://thomasokken.com/free42/

have been updated recently (2019).

I started the project in 2004, and the commit history goes back to 2005, but it's only been on GitHub for a couple of weeks.

THANK YOU THANK YOU THANK YOU for maintaining this project, Thomas!

I’m sure it’s a hard effort to keep it running on so many platforms at once but it’s a incredible piece of work.

The calculator that got me through engineering school in the early 90s. Excellent little machine, but I was a bit jealous of the guy with a 48S.

You shouldn’t be. Today, I use an HP-42 as my desk calculator. It is a considerably better tool for that job than my HP-48, which is significant overkill. And if I have a problem for which the HP-48 might be the better tool, in actual fact Matlab is the right tool for that job.

The HP-42s hits the sweet spot for scientific calculators in the era of powerful computers. It is small enough and its interface is fast enough that it is still faster to do calculations on it than it is to fire up a calculator app.

I adore mine as well. Did you ever know about the speedup hack that was found back in the day?

https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv003.c...

I used an HP-28s to get through school. Like all of them, the battery door broke and now it's basically junk.

My desktop calculator these days is an HP-35S which is to find and inexpensive. I've been thinking about a Swiss Micro clone of the HP-15C but it's hard for me to justify the purchase.

My HP-28S still works after 30 years. The battery door is missing a corner but it still works!

I didn't know this was a common problem.

These days I mostly use PCALC on my iPhone. I like the ability to customize the number displayed lines from 4 up to 8. There's free version too : PCALC Lite

It's a very common problem. If you google "hp 28s battery door" you find a lot of discussion.

At one point somebody made a metal band that goes across the back of the calculator and holds the batteries in. They don't seem to be available anymore, but that's basically what I need because my battery door is in decent shape, but the case is cracking at the corners.

If you do a lot of calculations while reading paper books, or while writing in a lab notebook or on a clipboard, the HP-15C makes a great calculator.

The landscape form factor, in my experience, is less likely to get in the way of my book or paper than a portrait form factor. Probably because we write left to write then top to bottom, and read the same way, and so a landscape form factor overlaps fewer lines than the same area in portrait form factor.

A phone calculator in landscape mode is not as good for a couple reasons. First, phones tend to turn off when idle for a bit. It gets annoying to have to keep unlocking the thing.

Second, without physical buttons it is a lot harder to operate without looking.

This later problem could be addressed if you made a physical overlay that you could put over you phone screen, which covers the key section of the phone calculator, and has a hole over each key. Make the overlay thick enough that it is easy to feel where the holes are. That should provide enough feedback to let you use the calculator without looking.

(Fancier would be to make an overlay that actually has physical buttons. Make the buttons out of something that conducts touch, so that when you press it the button touches the screen).

Second, without physical buttons it is a lot harder to operate without looking.

The third is all the distractions of a modern phone.

The combination of textbook, notepad and pencil, and calculator, is perfect for deep study of a complex topic.

I have my wife’s HP-15C that she had in grad school. Unfortunately it had an accident and got doused in liquid soap. It still works, but drains the batteries in just a day or two, and I’ve never figured out how to fix it.

I agree that the 48 is overkill for most things; however, seeing more of the stack is really helpful.

Yep. It's one benefit of the SwissMicros DM42. (There are a few other minor upgrades to the original HP42S as well, much better display resolution and really long battery life stand out.)

You're probably right :)

It was rugged too. One problem I had years later when I went to start using it again was that it would drain the batteries too fast - they were seemingly always flat.

The original use case for the HP-48 was for surveyors and similar who needed to do serious calculations in the field but laptops weren’t suitable or even available. It is the perfect tool for that.

It is overkill on your desk if you also have a PC on your desk, unless you just prefer the interface I guess.

For some reason I’m so much faster on a calculator than with Matlab or something. RPN is designed to get you answers quickly, while Matlab.. not so much.

I have a 48 but now I just use my 50g. The build quality isn’t as nice but it’s a hell of a lot faster. If HP had bothered to actually port the software to ARM instead of writing a Saturn emulator it could have been maybe 25x faster, though.

Anyone try the Prime? It seems like it’s targeted for kids, but the screen looks nice.

Thank you. I will check it out.

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