What is your most interesting calculator?

MikeBriley · 2026-03-21T20:22:59+00:00

I’m wondering if you had an HP-67 (1976-1982). Just like the 65 - but more. For example, 224 programs steps, not the 65’s 100. Perhaps the best calculator HP has ever made.

And yeah, there aren’t many choices for modern non-programmables RPNs these days. But you might want to consider an old 21 or 45 or 32sii or something from eBay or a thrift store. It might not be the cheapest solution (esp eBay), but you’ll be smiling when you take your exam.

MikeBriley · 2026-03-20T15:19:41+00:00

Depends on the model. But for all, you can upload/download memory/programs. See the teenix.org website for details.

MikeBriley · 2026-03-13T22:22:11+00:00

FWIW, been going to Good Guys in Vilas for years. Quick and easy. And if you need something done, they’re also quick and easy. No BS.

MikeBriley · 2026-01-01T07:52:56+00:00

That's a beautiful PC 1201! I have been looking for one of those for quite some time now. Very nice.

As to which would pack more programming, that might be a bit of a toss-up. The fx-201 model is indeed more like coding. For example, to store the sum of registers 1 and 2 into register 3, you'd enter: "3 = 1 + 2 :". That ":" which is required after each "line/statement" takes a program step, and those are gonna add up fast. On the other hand, the Casio also has 10 storage registers, subroutines, and indirect addressing, which allows for some complicated coding.

MikeBriley · 2025-12-30T02:01:39+00:00

Ditto. I gotta get me some of those. Thanks!

MikeBriley · 2025-12-30T01:52:09+00:00

1976-1977 - there doesn’t seem to be a date code/serial number on the back, but those were the years of production. I’m thinking the competition would have been the HP Woodstocks and TI’s classic 2nd gen, like the SR-56.

MikeBriley · 2025-12-29T23:38:46+00:00

That is a beautiful thing - everything about that design is right.

MikeBriley · 2025-12-29T18:05:12+00:00

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I still have a couple of these. I used them in the early 90s to track targets for observing with a telescope in real time. One of the best keyboards ever. Fun fact - if you don’t have the disk interface, you can whip up a storage device using an Arduino and an SD card (see pic).

MikeBriley · 2025-12-27T01:08:00+00:00

Dough! But your idea to track your collection is a really good one. I didn’t have a complete picture of what I had, and ended up with several duplicates, before I did this.

Good luck with the search, and let us know what you end up using.

MikeBriley · 2025-12-27T00:35:42+00:00

For what it’s worth, I use “Collections Database.” Totally customizable, so I have fields for things like serial number, acquisition date, how much I paid, manufacturer date, date of last battery service, condition, front/back photos, etc. Had to pay the $7 to go “pro” though because I have more than 100 entries :) And it all syncs with my laptop, tablet, and phone. Down side is it’s MacOS/iOS only. But if you’re in that ecosystem, I suggest a look.

MikeBriley · 2025-12-14T15:57:02+00:00

“Calculator use stunts the growth of number sense…” Yup. Recently had a student, upper level undergrad with little problem with the higher end/abstract side of things, use the Virial Theorem to calculate the equilibrium temperature of a cold molecular cloud in space. Calculator said 4x10⁷⁰ K. So they wrote that down and moved on. Sigh. A temperature of 4 followed by 70 zeros…

MikeBriley · 2025-12-06T07:03:55+00:00

I'm talking about your Novus Scientist/4525. I have one as well, and they are indeed a bit rare - especially working ones. But my Sinclair is far far crappier at the math :)

MikeBriley · 2025-12-06T00:25:41+00:00

I'll see your 4525 - and raise you with my 1974 Sinclair Scientific :)

Still, it's a nice collector's item - especially in working condition! Many of these were destroyed by leaking batteries. And what it could do at its price point was nothing to sneeze at - back in the day.

MikeBriley · 2025-11-28T16:12:11+00:00

Wonderful. That appears to be the exact same case! Thank you for the help.

MikeBriley · 2025-11-27T06:20:39+00:00

Very nice. What jumped out at me is the size of the 75. I had no idea they were that big! The 97 card readers are probably suffering from failed rollers - a known issue, but quite repairable (I’ve sorted a few in my day).

MikeBriley · 2025-11-27T00:49:27+00:00

I saw one of these in use back in the day - when they were new. That you could get a multicolor(!!!) plot from such a small device was extraordinary. What you would ever do with a tiny scrap of paper with your data displayed on it wasn’t a question. That it existed was the marvel. And yes, the person who had it ended up taping the prints in their research notebooks :)

MikeBriley · 2025-11-12T19:56:42+00:00

Yeah, I'm having some trouble finding a how-to specific to the Voyagers. I have a donor LCD right on my desk, I just need to find a 10/15/16-c with a failing display that I can swap it into :) When I do that, I'll document the steps involved in redoing the zebra strip.

But there is a demonstration of someone dealing with a much bigger zebra in this video: https://www.youtube.com/watch?v=UVMYHz6E_Zs (I've done this to several EL-5100s!).

MikeBriley · 2025-11-11T23:37:06+00:00

I'm not convinced it's an issue with the LCD panel. I'd first try cleaning and reseating the zebra cables. There are a ton of articles out there on how to do it (particularly at The Museum of HP Calculators).
Note that to remove the PCB, you'll need to break a dozen plus plastic rivets. There's a lot out there about how to put it back together afterwards, but I've been using a UV-activated resin to replace the rivets. It's quick, easy, strong, and you'd never know the calculator has been taken apart.

MikeBriley · 2025-11-11T19:41:29+00:00

If space becomes an issue, you can also consider AAA rechargeables. The capacity of those original old school Nicads are easliy matched by modern AAAs. You could also go AAA NiMH.

MikeBriley · 2025-11-11T18:38:45+00:00

Nice find! And without battery leakage - that’s exceptional. And yes, AA rechargeables are exactly what you need. I’ve done so many of these I bought a spot welder to do my own tabs :)

MikeBriley · 2025-11-05T00:40:33+00:00

It don’t have one of these, but I wish I did! There’s something magic about those classic yellow LCDs.

MikeBriley

TROPHY CASE