When humans counted on their fingers, everyone had a state-of-the-art (at the time) calculator at all times. But as we got smarter about calculation, we missed that convenience. When slide rules were king, techies were known to carry them around like swords swinging from their belts. These were replaced with electronic calculators, some also swinging from belt loops, but no matter how small they were, they still were not that handy, no pun intended. That changed around 1975. The Time Computer Calculator company produced an amazing calculator watch for Pulsar. At the time, Pulsar was a brand of the Hamilton Watch Company.
There were a few problems. First, the watch was thick. Despite its size, it had tiny keys, so you had to use a little stylus to push the keys — not as handy as you might wish. On top of that, 1975 display technology used power-hungry LEDs. So, the display was prone to turning off quickly, and the batteries died quickly.
Unsurprisingly, Hamilton, in conjunction with Electro/Data, had earlier rolled out the first LED watch in 1972. With an 18-karat gold case, it went for a cool $2,100 — a whole lot of money in 1972. The first calculator watch was also gold and went for almost $4,000. Soon, though, they brought out a stainless and a gold-filled version that came in at under $500.
Hewlett-Packard
For such a hefty price, these calculators didn’t do much. They were generally “four-bangers” with a few extra features, but they were no scientific calculators by any stretch of the imagination. The HP did have time and date calculations and could even use a stopwatch as a data source.
More calculator watches appeared directly from Time Computer Calculator Company and several others, but none were ever more than an expensive novelty. There were a few from companies like Seiko and Citizen. LCD screens would wipe out LEDs in watches, including calculator watches
Some lesser-known companies took their shots. Uranus Electronics was one. Hughes Aircraft also created an LED calculator watch with the name Compuchron.
Citizen had unusual round watches with tiny buttons around the circumference, including some that had scientific functions. These were the first calculator watches to use LCDs.
Seiko’s first entry had truly tiny buttons (see the video below). However, the C-515 had some of the nicest keys of the era, although design-wise, it was a bit blocky.
The National watch was a big hit in 1977 and a marvel of miniaturization. You can find some very detailed teardown pictures on Wikimedia Commons.
It is hard to say how many of these calculator watches were made and sold. Most are rare, and you would imagine the gold ones were not big production runs. Even the cheaper models seemed more like stunts than mass-market products.
Clearly, there was some demand, but things remained a niche market, and smaller players weeded out quickly. The calculator watch market was relatively sleepy until 1980 when Casio decided to make them.
Casio
The CA-50 was popular, and it appeared, along with the similar CA-53W, in popular movies, including Back to the Future II and III. These had tiny buttons, but you could carefully use them with your fingers. Some models had raised buttons. Others had flat buttons. A few even had a form of touch screen.
There were many variations in the Casio calculator watches. Some could store data like phone numbers and addresses. Others had scientific functions, like the excellent CFX-400 or the less-capable CFX-200. The CMD-40 even had a basic remote control.
The nicer models had metal cases, but many were plastic. There were even some that looked like a normal analog watch, but the top would flip up to reveal the calculator display and keyboard. Tricky to replace the batteries on those as you can see on the video below.
Calculator watches became something of a fad, especially with the pocket-protector crowd. However, like all things, they faded in popularity over time and now most are collector’s items.
Today
You can find cheap calculator watches readily on the usual Chinese import sites. Casio still sells some vintage-series calculator watches, and there’s a brisk used market for the watches from any manufacturer. However, outside of the collectible value, most people switched to small calculators, PDAs, and — later — cell phones and smartwatches.
I owned several Casios, including a flip top and the FX-400. I also had the nice boxy Seiko. I don’t think they have made it unless they are hiding in a box somewhere waiting to be rediscovered. Which ones did you have? Do you have them now? Do you ever really use them?
Before you take me to task for not mentioning Sinclair’s wrist calculator, I will point out that it wasn’t really a watch. It was just a calculator that strapped to your wrist.
There have been DIY calculator watches, of course. It would be even easier to produce one today than ever before. It might be fun to grab one of the new ones and give it a brain upgrade. Let us know if you take up the challenge.
Featured image: “Casio Gold Calculator Watch” by [jonrawlinson].
I had a Casio with raised buttons in the 80s… Was the ‘cool’ thing in those day for us geeks. Plus the calculator in the shirt pocket or on a belt loop … Still like it better than typing on a virtual calculator in a smart phone … Ie. Physical buttons, dials, switches trump any screen based simulation… Whether calculators or cars.
I found the raised buttons to be a vulnerability. I tore two buttons off when the watch scraped against something.
And if you want a bit more functionality, there’s always Travis Goodspeed’s Goodwatch project!
https://github.com/travisgoodspeed/goodwatch
Had one of the Casios, around the early~mid 1990’s. (Black body) They had a scrolling memo and phone# function…and yes it would accept swear words.
I was working as a welder at the time and even with it inside a heavy glove, the arc heat kept melting the keypad membrane loose.
The membranes kept finding their way to the floor and the adhesive side would get covered with grit and metal dust. Trying to clean them seemed to take away the markings also. Arrgh!
After about 3 of them succumbed, I finally bought one more calc-watch and tossed the working watch in a drawer somewhere. Hopefully I remembered to pull the battery!
Wonder if I should look for it ( & see what exact model) and check what the Ebay crowd is paying nowdays?
Cool story bro. If your watch is melting you’re probably not doing just this wrong.
If your watch is melting, Salvador Dali may have had something to do with it.
“They had a scrolling memo and phone# function…and yes it would accept swear words.”
Hi, the name for such devices used to be “electronic organizer” or “data bank”.
They were made en masse in the 90s, often with a simple PC-Link (RS232 cable with TTL levels) or an irDA port (photodiode for reception).
Some did also read a black/white flicker code from an application window drawn on a CRT monitor.
Anyway, just saying. I don’t mean to educate, but these things are nolonger being common knowledge.
Looking back, it’s been 30 years from were we’re now.
Joshua. The refresher of the info is appreciated. Most of us are here to learn, I believe.
And some of us graybeards are just simply starting to feel things fading with time.
And fwiw, the Casio functions (plus simply always having it with me) definitely helped with my income while re-organizing those manufacturing stations.
I still have my casio dbx100 with full lcd XxY display! The membrane keyboard deteriorated from time but still functions.
This is from a time when cultural things such as mathematics still mattered to the population.
Or maybe I just get it wrong and people had bought them because of their dedication to money making?
To always have a calculator at hand (pun intended) to calculate prices, make a cost calculation etc? 🤔
On a second thought, not everyone can be an American by heart, hi and these wrist watch calculators were made around the clock, err, the globe.
Anyway, maybe it doesn’t matter that much. 🤷 These calculator clocks were interesting for other sakes, too.
Some included a little LCD game, an alarm or a little melody (music box).
Other cool wrist watches also included an FM radio with a 3,5mm headphones jack. The headphones doubled as aerial, I think. 🙂
I built a Sinclair wrist calculator kit when I was at school. I thought it, and I, were well cool. With hindsight I’m not so sure…
http://www.vintagecalculators.com/html/wrist_calculator.html
I always was curious about why if calculator watches were expensive keychain-sized calculators were not.
Because dad never wanted to buy me one but with my allowance could have a keychain calc, with its own carrying case to boot. And nice looking too with a metal body & keys.
I wore various plastic Casio calculator watches for nearly 40 years, finishing up with a DBC-32 Data Bank. Earlier this year I decided it was time for something a bit more grown-up, so started wearing some nice mechanical Seiko 5 Sport watches. The tiny buttons on the Casio were hard to use and today there is always a device with calculator functionality at hand, so I’ve never missed the calculator watch.
Back in the early 1980s, a comedian asked “What is the purpose of a calculator watch? I mean, when was the last time some asked you; ‘What time is it? Also what is the Square Root of 67?’ “
Today, they’ll ask you about your heart rate and sleep patterns.
I had several of the casios and they kept breaking. There was a flexible plastic membrane between the buttons on the side (time adjust, light, stuff like that) and the internal PCB and it would crack and then you lost those functions. I quite liked them besides that, and at the time definitely did not have any way to try to fix those.
I knew two HP engineers (both mid level managers) who got HP01’s so I got to touch/play with one. Pretty cool.
I remember one of my schoolmates getting a calculator watch in the 80’s, hot damn he was the coolest guy in the school for a minute or two.
Having a digital watch at all was pretty cool, everyone would set them to beep on the hour just so everyone else in the class knew you had one. One of my teachers was very tall and would confiscate them by lifting a ceiling tile and putting the watch up there… I think my old Casio might still be up there.
No.
He was never the coolest kid in school.
Not for a second.
I had a cheap calculator watch in the 70s, Jr HS.
I thought it was cool, but I was already a cast out.
The cool kids just laughed.
you had the opportunity to name the article “history you can watch” and you missed it :P
I’m wearing a Casio Databank right now. The selling point for me is actually the fact that it displays time down to the second as well as the month, day, and weekday, all of it on the default screen with no interaction. But I do use the calculator every once in a while.
Well as soon as I get around to it, I’ll add a calculator app to the Pinetime operating system and you can add that to this article!
There are a number of members of hpmuseum.com/forum who have written calculator programs, both for computer/phones as well as various chip families.
Some are reverse engineered from historic HP calculators (Scientific, RPN, CAS, Financial)
Check it out, there may already be the software you’d need for the Pinetime (I am ignorant of which processor it uses.)
The HP-01 was far more than other watch/calculators of the time. Its architecture was that of a micro-coded processor, spread across a number of chips packed inside the case. It was thick, and rather heavy, but its ability to do calculations with dates and times was unique. For example, it was easy to determine what day of the week was November 12, 1956; or how many days between January 5, 1942 and March 14, 1954?
It also had a stopwatch accurate to .01 seconds, and one could use the stopwatch while it was running in calculations. For example, suppose you are making a long-distance phone call (back in the day), and want to keep track of how much money in charges you’ve racked up. If you know that it costs $0.15 per minute for the call, you can put in the .15, and have the watch display the running total of charges, updating the display each second once the stopwatch is started. It also had a countdown timer that could ring the alarm when it got to zero. It also had a regular alarm that you could set to a given time, and it’d beep at you when the time arrived. Most of the other calculator/watches of the time were just a clock chip and a calculator chip with multiplexing to select which one got input from the keyboard and output to the display.
The Gold HP-01 was prized in oil-wealthy Saudi Arabia, and a large batch of them was purchased by a Saudi prince to give to his friends as gifts. The stainless HP-01 was identical in function with a less-expensive case and band. Today, the HP-01 is a valuable collectible, with operating examples of the Gold watch in fine condition with all accessories selling for upwards of $7500 and sometimes more. More info:
https://archive.org/details/Hewlett-Packard_Journal_Vol._29_No._4_1977-12_Hewlett-Packard
What a nice surprise to read about one of my passions on Hackaday! I own a few of the calculator watches you described and I produced the video of the Seiko C515 that you included. Of my 100 or so vintage digital watches, I only wear a few regularly and the C515 and HP-01 are two of them. They were so cool to wear in their day and amazingly I even see them occasionally on the wrists of the smartphone generation.
I have a Casio CA-90, bought it in Saudi Arabia in 1982. ;) Recently I overhauled it, in the hopes to get another 30 or so years out of it.
Casio basically had two designs: one with a 4×3 keyboard and 7 buttons on the sides, and one with a 4×4 keyboard and 1 button on the right side.
The CA-90 has the 4×3 keyboard. It just looks aesthetically more pleasing than the 4×4 keyboard type. And it’s smaller, I have quite slim wrists.
One day I’d like to have a CFX-200. But boy, most are beat up but still cost their weight in gold.
One day, I might make an RPN calculator watch like the µWatch (https://hackaday.com/tag/%C2%B5watch/). With today’s even more miniaturized switches and displays, it should be possible to make the watch smaller, while still adding another row of keys (7 more keys). I found the EA DOGM132L-5 display, which is reflective, only 2mm thick, and easy to solder. And there are literally hundreds of low-profile miniature tactile switches to choose from, although not so many with a low operating force.
I would like to introduce my daily wear, analogue calculator watch: The Seiko Flightmaster Pilot SND255p1. When we’re talking about computers, this little thing has all the slide-rule capabilities of your standard (E6-B) for all your time/fuel/distance needs. While it’s neat to use the cocktail toothpick to do trigonometry and type 80085, this little gadget saves time and lives and barely runs off a battery (quartz for the movement and that’s it). Would love to see more slide-rule bezel apps/physical models, especially low-power or fully analogue like this out in the wild.
Good point – there were and still are watches with slide rule like some Casio Edifice.
FYI,
https://millenarywatches.com/seiko-flightmaster-snd255-review/
But what does this sentence from the link hint?
“Another nice feature of this movement is that it has a hacking function.”
Heh, that does sound different to modern ears. But at one time it would have meant that you got everyone to set their time in advance but wait to start it ticking again. When the designated person believed the preset time to have arrived, they would call “Hack!” and everyone would start their clocks at once, so they’d be synchronized for awhile until drifting apart again.
I never got into the smart watch craze, but I love watches. I have a Casio calculator watch that I keep in my daily rotation of favorite watches! Great conversation starter haha!
An honorary mention should go to Breitling who added a circular slide rule to the Navitimer in 1952. Still in production today…