Curta mechanical pocket calculator - photos

The Curta is a mechanical pocket calculator that was popular before electronic pocket calculators rose to prominence in the early 1970s.

The Curta is the brainchild of Curt Herzstark, an Austrian inventor who designed the calculator just prior to WWII. Imprisoned in Buchenwald in 1943, Herzstark received favorable treatment for his technical expertise, and was recruited by the Nazis to assist in the construction of his mechanical calculator, which they had planned to give to Hitler as a gift for winning the war.

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Hitler never did get his war victory gift. Buchenwald was liberated in 1945, and Herzstark successfully manufactured his mechanical calculator. Curtas enjoy a resurgence in popularity today, and models in good condition sell for around $1,000.

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Yes, Curtas can be 3D-printed, but they are too intricate for home 3D printers to handle at scale; 3:1 versions are more common.



More:

https://en.wikipedia.org/wiki/Curta
Concentration Camp Inmate Invented World's First Pocket Calculator - SPIEGEL ONLINE


Previously:

https://www.homemadetools.net/forum/...6452#post83701

Maybe Clickspring will tackle building one (from scratch, naturally :-) after he finishes the Antikythera Mechanism build... I saw one of those a very long time ago; my dad worked at Kitt Peak Observatory and while visiting one day I met one of the astronomers, who had one (well used) on his desk next to his slide rule. No, he didn't let 10yo me play with it :-(

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Originally Posted by bruce.desertrat

Maybe Clickspring will tackle building one (from scratch, naturally :-) after he finishes the Antikythera Mechanism build... I saw one of those a very long time ago; my dad worked at Kitt Peak Observatory and while visiting one day I met one of the astronomers, who had one (well used) on his desk next to his slide rule. No, he didn't let 10yo me play with it :-(

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I think you just hit on something Chris might be interested in doing! I can't even imagine how cool it would be if he took on this one. Still desperately waiting for continuing episodes on the Antithykera Mechanism; what I like most about it, though, is his exploration of ancient tech, and how things might have been done, given materials at the time. Really cool stuff. Maybe we could encourage this mechanism for his next project.

U of T, 1960. A prof pulled out a Curta in front of our large second-year class to do some calc to show off. It's the only time I've seen the device. Most of us had Pickett and Eckel or K & E slide rules, some in leather holsters hanging from the belt. The odd juvenile engineer with literary ambitions would stencil "Sly Drool" on it. Scientific American always carried ads for the Curtas, as well as for never seen but intriguing "super long" cylindrical slide rules.

I hear you about the ancient technology side videos. I think I've watched the one about making the indexing plate a half dozen times.

Vololdar,

Your comment brings back fond memories.

From being in junior high through high school and then four years in college (10 years total) I used a yellow-colored aluminum Pickett slide rule with a leather holster (not on my belt but as as a protective case held under my arm while carrying books and a three ring notebook). It wasn't until my second year in graduate school in 1974 for a MS and PhD in geophysics that I finally used an electronic calculator. In 1974, the geophysics dept. shared an HP-35 and HP-45 for the grad students to share and my use of the slide rule diminished. However, using a slide rule required keeping track of the order of magnitude and dimensions to make sure the answer really made sense. I still keep that discipline.

By then almost all of my research calculations were performed for "free". We no longer used the more costly central campus data center consuming my ONR (Office of Naval Research) grant money because we were using a 16-bit Data General Nova 1200 minicomputer that several of us set up in a spare lab. Within a few months we added disk drives and a pen-plotter. Getting the DG Nova 1200 to boot-up wasn't easy in the beginning but we eventually overcame the crude manual start-ups by adding an EPROM BIOS. Before the EPROM, we would use the front panel toggle switches to direct the Nova to read a mylar tape reader protocol containing a simple boot-up BIOS to read a BASIC interpreter.

Within two months we had a FORTRAN compiler and link-editor running. I received my PhD in geophysics by 1978 but by then I was also an expert and an investor in computer technology and using slide rules was history. An interesting book in the early 1980's about a Data General 32-bit computer is entitled "The Soul of a New Machine" at https://en.wikipedia.org/wiki/The_Soul_of_a_New_Machine land long after my experince on the obsolete 16-bit Nova 1200.

Regards

Paul Jones

I came of age just as the slide rule was relegated to history; never did learn how to use it effectively. Still have my dad's 8" K&E tucked away somewhere...

I was a HS junior when the first affordable calculators hit. HP and TI had these insanely expensive ones, then National Semi (IIRC, this was ca 1974-ish) came out with their calculator-on-a-chip; 4 functions, fixed 2 decimals, 9 places, LED numbers. My electronics teacher at the time announced in class that he'd seen them at Walgreens for $19.99. (about $100 or so today, I just looked it up!). It was amazing. I used the heck out of that thing and it firmly fixed how to keep track of the decimal point in my head.

ON my desk at work I have the display and keypad of a Wang calculator given to me by a friend, no idea where the rest of it went... http://www.oldcalculatormuseum.com/wang360e.jpg

I'm sometimes tempted to clean it up, and toss in a RasPi into it to resurrect it as a calculator...just to show how far we've come.

For folks too young to remember "slip sticks", there are numerous emulators on the interweb, such as this simple one...

http://nsg.upor.net/slide/

or you can build your own, or choose from a list of old-time favorites like the K&E log-log, deci-trig, my old pal...

http://nsg.upor.net/slide/sryae.htm

This one looks like the Pickett, and has a movable cursor...

Virtual Pickett N909-ES SIMPLEX TRIG RULE with METRIC CONVERSION Slide Rule

Detailed instructions on how to use one...

http://www.sliderulemuseum.com/SR_Course.htm

I took a physical chemistry course that involved endless problems with variables that ranged over ten or twenty orders of magnitude. I would have killed for a digital calculator.

In HS, I was able to get a Post Versalog Slide Rule in preparation for college, but still had some time using it in the HS math course.
I felt like it was breaking the folks' bank account at the time....an expenditure of $25 !! ..."you better study hard, kid"
I used it quite often and it sure made the courses easier, but I was always disappointed with the lack of accuracy, even tho' most math answers only needed a couple of decimal places for the profs to pass them.

After about 50 yrs, even tho' it was in excellent shape with the leather "holster" like new, I decided to sell it.