DM41x: a modern take on the HP-41CX | Hacker News Reader

DM41x: a modern take on the HP-41CX

swissmicros.com

101 pointsjmspring74 comments

I recently purchased a HP 48GX, and its portable IR printer buddy (printing out pixelated graphs onto a paper roll is oddly satisfying), because I always wanted one when I was a kid. I had an HP 48G that I cracked open and soldered extra memory into some 25 years ago, but I was always jealous of the 48GX. So, when it became clear the COVID-19 pandemic wasn't going to be even remotely short-lived I decided to finally splurge on a 48GX to satiate my childhood dreams (aim high kids!) and to see if I could get it to act as a probe endpoint for my company's Modality analysis software.

I absolutely love the 48GX, and playing around with it has been fun as I'd hoped (including the esoteric land surveying software expansion card), but if SwissMicros made its own version I'd buy it in a heartbeat. A 40 Mhz Cortex-M4F under the hood of a homage to the 48GX would be awesome!

I loved my HP48GX back in the day. I wrote a bunch of tools for it (25 years ago!), including an emulator for that printer:

https://grack.com/code/legacy/hp48/hpir/

The HP48 font is there in the zip package as well if anyone wants to use it for any reason.

Ha! That's awesome, love it.

attempt were made https://old.reddit.com/r/eigenCalc/

That brings back memories. I cracked mine open and soldered the extra memory as well. I nicked a couple board traces drilling out the plastic rivets, but I found a couple vias I could solder at to patch it.

I still use that calculator today at work. It has nice base conversion with arbitrary bit depth.

My 48GX broke at the bottom of my bag in college, so I replaced it with a 48G. The G is still going strong, and I continue to keep it at my desk today.

Still using my 48G today. I used to have a 48GX as well but some (not old!) batteries leaked and ruined it.

In high school I wrote some RPL for it that would use a small 9V-powered 2400bps modem to dial into a local BBS and download my mail.

I still have my 1980s-era HP-11C, but I've almost never used it since college. If I need a calculator, usually I'm at a computer, and bc, dc, or a spreadsheet is readily available.

If I'm not at a keyboard, then the calculator app on my cell phone will do. Which just led me down the rabbit hole of Android RPN calculator apps. :o)

Still, there's nothing quite like the tactile feel of a classic HP calculator keyboard from back when HP really was Hewlett-Packard.

Any favorite, of the android RPN calculators? I've been using just free42 for a while.

That's what I ended up with as well... looks pretty nice. It'll be interesting to see how much of my 11C experience transfers over, at least, that which I remember in the first place. I've never lost RPN (mainly because of good old dc), but the programming is a different story.

I've been using Droid48 for maybe a decade now, it's very robust. Recently started playing with Emu48 with hp50g skin as well.

Any significant improvement in emu48 vs droid48?

Main improvement seems to be ability to use more recent firmware, so no more trying to backport pretty much a complete OS from hp49 to hp48 :)

I've been happy with realcalc, nice relatively basic scientific calculator. Or emu48 in 50g mode for when I need something more advanced.

I'm using 11CSciCalc on my MotoG7power. It's good (at least for keyboard layout and key-function -- haven't had occasion to try out its programmability for compatibility), but without the tactile feedback of the real buttons I have to visually monitor what actually gets entered, so I can't drop fully into the problem domain, not like I can with my HP11C.

It's my HP41CV that basically never gets used. Back when, I wrote a program on it, 'ampsr', to calculate ideals and then find the closest standard-value matches for a three-resistor attenuator network used as the gain-and-offset control of an opamp amplifier; it took 16 minutes for my HP41CV to arrive at the answer, and that was just selecting among the E24 "5%" standard-value array. My later Perl version, by comparison, is all but instantaneous even working with the E96 array and running on a 400MHz box. The HP41CV's programmability was great for its era; not so much, now.

I've used RealCalc for a few years. I paid a few bucks for the "plus" version. It hasn't been updated in years, but that's fine with me because it just plain works.

Same here. I have to sheepishly admit that I prefer infix notation, and RealCalc reminds me of the cheap Casio scientific calculators that I still use.

The first thing I look for in a calculator is that you can enter numbers in scientific notation without hitting a Shift button.

I'm very happy with CalcTastic, though it's not been updated since 2018 it still seems to work just fine.

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

I've been using RpnCalc by Edward Falk on Android for many years without complaint. Last updated 2017.11.

This is why I wrote a cell-phone-friendly frontend for my K interpreter: https://github.com/JohnEarnest/ok#mobile

I agree, though- dedicated tactile buttons will always be nicer for a calculator.

I'd love to have APL or K on a small calculator like the HP-15c just for the cool factor. With an SD card slot it would make for a really cool portable programming computer.

The physical keys is why I still grab my 30ish year old HP-11C for quick experiments, however it's hard for me to phantom a good experience with K on a single line display. We'd probably be better off with a portrait form factor, roughly 1/3 display, 2/3 keyboard. Getting switches with the HP quality and feel is the biggest problem.

EDIT: actually, porting oK to the DM41x might be the best option (putting stickers on remapped keys).

Closest I've come to that so far was getting oK running on a PocketCHIP. (Which is really just a matter of installing node and cloning the repo, thankfully.) The keyboard is less than stellar, but not too bad for trying little expressions.

I have an irrational reverence for my moderately modded PocketCHIP and pull it out every few months, but the keyboard is just truly awful. This is possibly a spiritual successor https://www.tindie.com/products/arturo182/keyboard-featherwi...

Yeah I should've explained that I think it would need a slightly larger screen.

I still have my HP-41CX that I got for high school graduation in the 80s. (I won't say exactly when during the 80s, so I can feel a few years more youthful.) It still works absolutely perfectly and is a true pleasure to use. The action of the buttons is still unmatched by any competitors and notably superior to all current TI calculators. Even the case is superior: durable but soft exterior, false bottom with extra padding, YKK zipper that will probably work for a century after I am dead. Even the rubber feet on the bottom are of superior quality: four really sizable feet that haven't worn at all after decades, and they obviously chose a good adhesive because they haven't fallen off, either. This calculator proves the famous Ben Franklin quote:

"The bitterness of poor quality remains long after the sweetness of low price is forgotten."

Question: why HP-41 over other things, like TI's TI-89?

The latter has, among other things, has two properties which make it really useful for day-to-day engineering use:

- Large screen which shows which expression you entered. You can spot a typo easily, and then fix it!

- Unit support -- helps a lot, as it will ensure you are not adding meters to ohms. Or add meters and feet and it will just work.

Swissmicros seems to focus on the classic HP lines which were RPN based. I have a few HP calculators as well as a couple of SwissMicros and am happy to have the updated version.

They already make the DM42, with a large display.

But there is a large degree of throwback HP fanboyism.

Well it also may be the key layout. After years of using a certain HP calculator, you get used to the layout. I prefer the 32Sii. Some have primary keys for x^2, x<y, 1/x, PI, etc. if I designed my own I’d have 10^x and LOG(x) as primaries. All depends on what field one works in.

Anything non RPN sucks anyway.

And the DM42 runs free42, ... source is on their github

Well, once you use RPN, there is no going back. I truly despise normal calculators. I’d hate entering expressions anyway.

TI-89 has some pretty decent RPN programs ;)

Unlike the RPL series, they don't integrate with the rest of the calculator. And unlike RPN calcs like the 41 and 42, you can't program in RPN which many people find very easy to do.

TI's a fine calculator... for a middle school student.

> Question: why HP-41 over other things, like TI's TI-89?

One reason would be that you can buy a TI-89 Platinum today (though not a "classic: TI-89), the 41 series was discontinued in 1990 and the 42 in 1995.

A second reason is that classic HP calculators are legendary enough that people managed to set up an apparently successful company based entirely on cloning and evolving classic HP calcs, that's literally what SwissMicros is: the company started in 2011 with an HP-15 clone.

Ti is still out there serving what market there is for Ti-style scientific calculators, not so for HP.

HP's calculators were legendary at the time. TI's calculators weren't quite in the same league. The TI-89 is a later and much more refined design.

HP's engineering was literally state of the art and unbelievably sophisticated for the day. At a time when computers ranged from big-box desk stations to air conditioned room fillers and cost thousands to millions of dollars, HP put a small programmable computer in your pocket.

They're not particularly useful for modern math, and if you really want the same features you can buy app emulations. But like any other brand of tech nostalgia, some people imprint on the machines they first played with. Any excuse to own a reinvention of the original hardware is going to appeal to them.

40 years ago, the HP-41 had a whole ecosystem of add-ons that took advantage of the expansion ports. Today, I suppose, you’d be better off with just a USB port.

>The TI-89 is a later and much more refined design.

I've got both ti89 and hp50g. I seldom use the latter anymore.

TI-89 is slick, fast, responsive, a pleasure to use, something to study for its great UX.

HP50g is sluggish and a chore to use. It doesn't deserve the reputation.

This is particularly sad as the hp50g uses a relatively fast ARM cpu, whereas the ti-89 uses a plain 68000.

The HP 48/49/50 series is more of a competitor to the TI89.

The HP50G is a fairly extensive ARM based computer not a calculator. It is ridiculously powerful. It is discontinued now in favour of something pretty and shiny but vastly inferior.

>It is discontinued now in favour of something pretty and shiny but vastly inferior.

Similarly, TI is pushing some crap (TI-nspire) with vastly inferior UX to TI-89/TI-92.

Fortunately, TI haven't lost their minds yet. They still sell a version of the TI-89.

I am hoping that line does last. Otherwise, they'll be basically abandoning a market to whoever will have to pop up to serve it.

Yep. The NSpire is an awful pile of shit. I had one for a month.

I’ve taken to stock piling HP48GX’s when they turn up on ebay.

If you're into stockpiling them, it wouldn't hurt to get a TI-89/92+/voyage200 while at it, and see the best the other relevant calculator maker has to offer ;)

I've had hp50g for a long time, got a ti-89 recently and became enlightened.

RPN is really useful for observing intermediate results and comparing with a mental model of what would be reasonable scales. I use Emacs M-x calc quite a bit for this reason, versus a Julia/Python session when variable names and functions become necessary.

You are asking the wrong question. "Why use an RPN calculator", would be the better question. But there are still some answers, why an HP calculator. The build quality and the buttons on a HP calculator are just so much better, there is no contest. You say on a TI-89 you can spot a typo easily .. maybe .. I belive you catch errors better and quicker with an RPN calculator, because you allways see a result after each step. And if you need a TI-89 to stop you from adding meter to ohms, then I don't know .. Try a free RPN app and after a short time you will see, how it feels more natural to use this kind if calculator.

Doing a calculation chain with RPN does take a bit of practice to do correctly and efficiently. It's probably a little easier on the 42 because the display shows the Y register. That said I've been using RPN since I got an HP-55 in college (retiring my TI after a year--calculator prices were dropping fast at the time).

> And if you need a TI-89 to stop you from adding meter to ohms, then I don't know

Don't knock it until you've tried it. Though as usual, the HP calculators that have this capability (48/49/50 series and 28 series) have a better UI for using units. But either way, this is a form of type checking, which is pretty universally regarded as a useful and worthwhile feature in programming languages. It catches mistakes from errant keystrokes, lowers the cognitive load by not requiring you to keep track of how many places to shift the decimal point when converting between metric units and obviously makes things a lot simpler when non-metric units creep into your calculations (because you can directly add feet and inches without problem), and encourages proper labeling of units for the quantities you end up writing down.

Ok, I'm from europe, so I never had to deal with inches and feet. I also have all my calculators in engineering mode, because I have often very large and very small numbers (electronic). But that also depends on for what you use your calculator. I have an HP50g but the units menu is something I tryed in the beginning and think at least for me is not useful. And yes, an HP50g would be more like an TI-89.

If you like RPN check out Factor and Forth. It’s amazing!

1. https://factorcode.org/

2. https://en.wikipedia.org/wiki/Forth_(programming_language)

I am a big fan of the current HP Prime calculators, a clear case of the "give up in despair because cell phones exist, then later realize you've got years to rebuild your product with cell phone parts..."

Prime doesn't really have much in common with the RPN or RPL calculators. It has a legacy RPN mode suitable for four banger operations but it doesn't integrate well with the rest of the calculator. More of an afterthought.

These HP calcs have the most aesthetic keyboard. The key size, click feel, and font/color all much better than the competing TI models

I wonder if it would run any "synthetic" programs. https://www.perlpower.com/prisma/prisma-1984-ppc.pdf

My guess is no since it probably does not emulate the original microcode.

It is, in fact, an emulator running the original microcode. Yes, Synthetic programming and all (Multiple Hundreds) of plug in modules are available, including new ones written today -see http://www.hp41.org/LibView.cfm?Command=Recent for examples.

Oh God, how I miss the tactile buttons on my HP-48.

I spent the first several minutes admiring the SwissMicros site but I was nagged by the concern that the buttons would fail to meet my tactile expectations. Reviews say I should not have been concerned. I am grateful to have this link.

I have the dm42, along with hp predecessors. The buttons are legit. Over time, hard to tell given the Hps I have are 30+ years old.

This is really good to hear. The website for this calculator mentions the display and the case, buy I feared the keyboard would get overlooked. The keyboard on my 15C still works perfectly. I believe HP used gold plated contacts on the keys to ensure long life, but that doesn't explain how their tactile response has held up over the years despite regular use. Amazing.

My HP-41CV did eventually get a sticky key problem and then a battery compartment leak killed it. But I still have a couple of the landscape form factor calculators--a 16C and (I think) an 11C--that still work fine though they don't get a lot of use these days.

I had an HP-48SX when I was in high school. I later upgraded to a 48G. Its RPL language was quite extensive and I was able to write a few small games in my spare time.

My dad was an actuary and he had one with the optional expansion ROMs and card reader/writer unit ... learned programming on it.

I have one of their other calculators, the DM16 and it is glorious! I might buy this one as well. Their quality is fantastic.

I bought a DM11 recently. I was disappointed by the LCD. The characters aren't centered as well as the HP11, and there are 3 large stuck pixels that make it hard to read some digits. It was like this upon unboxing, but didn't seem worth it to do an international return.

Nice to have is the iOS app i41cx+ from AL Software, a virtual HP-41CX plus Computer Algebra System (CAS) based on REDUCE.

http://alsoftiphone.com/i41CXplus/

I'm not particularly interested in this one but I have to say that my DM42 is brilliant in basically every respect and I really hope they continue innovating and making these.

My favorite is the HP 28S. Mine still works perfectly and lives right under my monitor so it is within easy reach all the time.

I also have a HP 50g, but it's not as fun.

I used an HP-41CV for years until it broke. I did buy a 28 at some point after that and I just didn't care for it. I was looking at the SwissMicro HP-42 clone the other week. I could really be tempted by that or this one. But, honestly, I have a couple of the landscape HP calculators and those are more than enough for anything I do and I have a 41CX app on my iPhone.

I found this video of it: https://youtu.be/UrU4sGWt45M

I'd love to see a real programming calculator like the HP 16C . But without RPN as I never really grokked that :)

For me it just doesn't have enough on the DM-42, which I already own. Neat development though.

To me 41 seems more niche product compared to 42 rather than straight upgrade.

The 41 is what I'm used to so it's what I use as a phone app but it's the older calculator. Leaving aside differences in the original physical form (which were partly to accommodate the HP-41 expansion modules), the HP-42 is the more advanced calculator, albeit not really a direct upgrade.

The 1 button on my 35s just started missing presses yesterday. This is a timely link for me

You wanna carry two phones?

I don't carry my old HP calculator with me, it lives at my desk where it's been very useful over the years (less recently, but that's a change in job responsibilities than the utility of the calculator). And if I did have to carry it, it'd be in the shoulder bag where I have my notebooks, books, laptop and/or tablet. I mean, it's rare that I'd think to grab a calculator to bring with me but not also have the other things I'd want record/communicate with.

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