December 23, 2025, 10:23pm 1

recently I’ve fallen down the retro computing adjacent rabbit hole of 70s and 80s calculators, and specifically programmer’s calculators! units like the HP-16c and TI-Programmer, that offered base conversion, definable word length, and bitwise operations (all of these features in varying ammounts depending on the calculator, of course).

I’ve recently been scouring the web for information about these calculators, and though I’ve found a few things here and there, I’ve had trouble finding any primary sources on the topic (aside from user manuals for the calculators). I was hoping that some of you folks here would know where I can find archived magazines/catalogs/press releases/whatever discussing these calculators from the time when they were new.

I’d also like to just have some general discussion about them! they’re fascinating little gadgets, and I’m sure if anyone has interesting things to say about them it would be the folks here.

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TLovern December 23, 2025, 10:33pm 2

I still own and use an HP-16C. I’ve had it since the 80’s. It’s useful and hasn’t let me down…

I’m on holiday for Christmas and when I get back Ill try to flesh out some details on it and how I have used it over the years.

amenjet December 24, 2025, 5:07am 3

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EdS

December 24, 2025, 3:58pm 4

Hmm, the article says

As it turns out, this calculator-like device is actually a hand-held emulator for the older, 4-bit COPS microcontroller family.

An interesting find, though.

Another example - although examples are not what the OP asked for - mentioned recently by flibble in the stardot discord:

That’s the Casio CM-100 “computer math calc”

I see a page on TI’s TI Programmer with a photo:

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EdS December 24, 2025, 4:04pm 5

I see in Calculator Corner by Dick Pountain a review of the 15C vs the 16C in Australia Personal Computer (pdf, see page 91).

The two machines reviewed this month, the 15C and 16C, are the latest additions (don’t ask me what happened to the 13 and 14; did I miss them?) and they are both far more exciting than the 11 in their different ways.

The 15C is mathematically oriented and has a range of operations never before offered on a programmable — nor for that matter on many micros that I know of. These include complex number arithmetic, matrix manipulation, numerical integration and equation solving/root finding, in addition to the normal maths and statistical functions.

The 16C is called the Computer Scientist and will be of interest to all terminal junkies rather than the regular readers of this column. It is aimed straight at that slot which the Texas Programmer has had to itself for some years now — machine code programmer’s assistant. It has features that go well beyond what’s offered by the ageing TI machine and will I suspect find its way into a lot of computer labs as well as the homes of well-equipped hobbyists.

…

Aimed at a specific profession with 90 percent of what you need hardwired in and sufficient programming flexibility for you to write the other 10 percent, this seems to me a shrewd choice of direction — and one which will sell a lot of calculators.

EdS

December 24, 2025, 4:17pm 6

In Popular Computing Weekly, December 1985, a review of Casio’s CM-100:

It has all the normal arithmetic functions of course, but what makes it interesting for any programmer is that it can calculate and perform logical operations, shifts and rotations, not only in decimal, but in binary, hex, and Octal. You can switch freely between each mode, with automatic conversion. A nice trick - in fact the whole thing appears to be well thought out, with the machine-code programmer in mind.

EdS December 24, 2025, 4:49pm 7

In the 1985 book Advanced UCSD Pascal programming techniques we read

One drawback of this method is the necessity of specifying large (i.e., > 8000 hex) addresses as negative integer values. For example, the word at address FFFF hex is returned by calling peek(-1). (A hexadecimal calculator such as the TI Programmer or HP 16C is useful in these situations.)

amenjet December 24, 2025, 5:24pm 8

Another interesting thing about the COPS thing is that the device itself runs on a COPS400 series controller.

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amenjet December 24, 2025, 5:28pm 9

I know it’s not what was asked for, but the HP Prime has a moderately useful base conversion mode, as does the DM32. The R47 that I recently bought has, at first sight, the most comprehensive BASE-n mode I’ve seen on a calculator. I do use this type of calculator now and again and haven’t really found a good one, until maybe the R47. The R47 is an interesting device in itself, actually.

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that CPA thing is weird, I appreciate you bringing it up here! I bet a 6502, 8088, or z80 version would sell incredibly to retro folks nowadays, even if just as a toy. I don’t think it’s quite the same kind of thing as a programmer’s calculator (just because I don’t think it’s really a “calculator” except maybe in the way IBM used the word in the 50s (see: synonymous with computer)). another weird “should it count?” calculator is probably the Texas Instruments SR-22, which offered some base conversion features in 1973 (though, in floating point, which makes it seem a lot less useful to me for programming).

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EdS December 24, 2025, 5:49pm 11

I see NatSemi’s COP400 was preceded by the original COPS I:

That would be the COPS I of course, better known as the MM5781/2 and its derivatives, the MM5799, MM57140 and MM57152. These microcomputers were released in 1976 and were made on a volume PMOS process. They were designed to be inexpensive and simple to use. The design of the 5781/2 actually started with the MM5734 which was a single chip accumulating calculator chip.

And we see a couple of 1979 calculators (err, actually flight computers) by Navtronic used these: navtronic 16 navtronic 1701

drogon December 24, 2025, 6:19pm 12

Programmers Calculators or Programmable Calculators?

Or both?

Here is a little anecdote… It’s 1980 and I had just started university. I had (still have) a Casio fx502p programmable calculator.

Part of my course was maths and we were learning about iteration - Simpsons or Taylors or something. I really don’t recall. Basically the same calculation many times putting the result back into the calculation until the difference was minimal (convergence).

So myself and friend who also had the same calculator punched the sequence into the calculator and let it run and within a minute we had the result.

I recall the lecturer not being impressed - he really did want us to do every step of the calculation on paper - by hand.

The irony? It was part of a programming course. We argued that we were programmers and he very reluctantly relented.

So it was a programmable calculator for programmers.

-Gordon

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EdS December 24, 2025, 7:23pm 13

You could, I suppose, write a program to do bitwise arithmetic?

For myself, I’ve always been comfortable with hex (I say always, that’s impossible) but never comfortable with octal, with the single exception of unix permissions.

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“Terminal Junkie” is a term for computer user I’ve never even considered before, let alone heard, lol.

also, looking at this article, and one you posted on the CM-100 reveals the startling information that the HP-16c cost $199 in 1982, and the CM-100 only cost $17.95 in 1985. (in 2025 dollars thats $668 and $54 respectively), the HP-16c is definitely the better device (what with programmability and all), but that’s just a crazy price difference for two very similar devices in just three years.

I find most people (well, not most people, but most computer nerds) are probably in the same position with regards to hex vs octal, including the Unix permissions (I assume octal would just be entirely forgotten in the modern world without them). but I could see these calculators being extra useful as reference tools back in days when tons of processors and computers all acted wildly differently, and multiples of 8 weren’t yet the universal standard for computer word length, just look at this blog post that shows off some weird Octal shenanigans with a non-standard ASCII implementation on an HP minicomputer (which I also found while looking for info on the 16c)

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drogon December 24, 2025, 8:37pm 16

Started in Hex (6502, etc. ) but then I was exposed to a PDP-11/40 - complete with Unix v6 and the keyswitch entry and LED display… And it was Octal. (17770 load address, run - probably)

And that was weird.

DEC history suggests a strong liking for Octal, even when the machine was natively 16-bit where HEX was more “natural”.

In recent years I’ve used (and owned) a PDP-8 where octal naturally rules the roost as it were, but it’s still a bit of an historical oddity for the most part, I feel.

-Gordon

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I bought this Casio back in the mid-to-late 1980s. Still working although I did have to repair it a few years ago by reflowing a few dried-out solder joints.

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gtoal December 25, 2025, 4:26pm 18

You could have a chat with an old pal of mine from Eindhoven, Ernst Mulder: https://calculator-museum.nl/?overview-programmer - he’s pretty knowledgeable about all things calculatorial…

amenjet December 25, 2025, 4:46pm 19

The SR-22 is a fantastic thing, isn’t it? Does it not do integer conversions? I thought it did after a quick look at the manual. They seem to be very expensive, unfortunately. The calculator uses the TMS0200 chipset which looks like a good candidate for ROM dumping and emulation. I don’t think the SR-22 has been dumped. A lot of TMS0500 series devices have, thoiugh, and the same technique should work.

amenjet December 25, 2025, 4:49pm 20

Back in the 80s I really wanted to build a calculator that ran on a Z80 and allowed Z80 assembly/machine code. I wasn’t able to do it back then, but now it would be very doable. I’m not sure what demand there’d actually be for it, but just after I got a CPA I started thinking along those lines again…