YACS 2.0 - Yet Another Curta Simulator 2.0

USING YACS

Operating the Curta Simulator

Setting a number

Drag the slider up or down with mouse button pressed.
Here 163 is entered on the setters.

Turning the crank

Click the crank handle to start a crank cycle.

The higher you click on the handle the faster the turn.

Speeds are 1, 3, 9 and 27 s

Extending the clearing Lever

For easy use the clearing lever can be extended.
Click any part of the lever to extend it.

Folding the clearing Lever

The clearing lever must be folded to store the Curta in the storage container.
Click the clearing lever position plunger to fold the lever.

Clearing CCW Very Slow

Click on any of the 4 colored section of the clearing lever ring to start a clearing action
Here we start a Very Slow Clearing Counter Clockwise (CCW))

Clearing CCW Very Fast

Click on any of the 4 colored section of the clearing lever ring to start a clearing action
Here we start a Very Fast Clearing Counter Clockwise (CCW))

Toggle the main mode between Addition and Subtraction

Click the Crank handle to toggle the adder mode between Addition and Subtraction.
Here the adder mode is Addition

Toggle the main mode between Addition and Subtraction

Click the Crank handle to toggle the adder mode between Addition and Subtraction.
Here the adder mode is Subtraction.
Note the red ring under the crank handle to indicate Subtraction mode.

Set Turns Counter mode to Increment

Drag the Reversing Lever up for Increment mode.

A crank turn with the adder in Addition mode increments the Turns Counter
A crank turn with the adder in Subtraction mode decrements the Turns Counter

Set Turns Counter mode to Decrement

Drag the Reversing Lever down for Decrement mode.

A crank turn with the adder in Addition mode decrements the Turns Counter
A crank turn with the adder in Subtraction mode increments the Turns Counter

Rotating the Carriage with the cover visible

Click on the digits 1..6 on the underside of the carriage.

1 .. x 1
2 .. x 10
3 .. x 100
4 .. x 1000
5 .. x 10000
6 .. x 100000

Rotating the Carriage with the cover removed

Click on the shaft to rotate it to the x 1 position.

Calculating 12345 x 298

Calulated as: 12345 x 298 = 12345 x 300 - 12345 x 2
This way only 5 crank turns are required.

Set 12345 on the Setters

Set the carriage to the x 100 position

Crank 3 times to caluclate 12345 x 300

Set the carriage to the x 1 position

Set the Adder mode to Subtraction

Crank 2 times to caluclate 12345 x 298

Done...

12345 x

298

= 3678810

ABOUT YACS

Current Version

VRML: loading...

Why did I do it

For two main reasons:

To learn a little VRML programming
Because I feel the Curta Calculator is a real beauty

My first exposure to the Curta was when a teacher showed us a Curta in our classroom.
It really was an amazing little machine. We were each allowed to do one easy calculation on the Curta.

That was early 1964, not long after JFK was killed in Dallas. The Royal Dutch Air Force crashed an F 104 Starfighter every few months and there was Robot Archie, a fictional comic character known in the Netherlands as Archie de Man van Staal.

Yes:

In the past everything was better... even the future.

...
>> Fast Forward 44 years >>
...

After searching the Internet for a while I discovered that it was called a Curta.
The good thing is that there is plenty of information on the Curta.
The bad thing is that they are now collectable.

Not willing to spend 1000+ dollars on the real thing I decided to build my own.

Because I do not like to get tired or dirty I soon settled for a virtual one.

I already did a few things in VRML, so it was a logical choice to use it for the Curta.
VRML 2.0 allows for basic animations, and for more complex things you can use JavaScript Nodes.

All you need is a PC, and a little time :-)

How Was It Done - The YACS Classic edition for BS Contact - 2008

To get things done I decided not to

make Power Point (TM) presentations
write Word (TM) Document
use TeamTrack (TM) (who needs it anyway)
use ClearCase (TM) (an over engineered piece of shit)
use Visio (TM) for drawings
use a 3D tool or CAD program

but

type in basic VRML code using the splendid VrmlPad editor
draw with a pencil on paper
use an eraser for corrections

and

make it work (prove that it can be done)
make it nice (refactoring code)
make it fast (but only where it makes sense)

At first I used a lot of information from the Internet and a set of drawing of the outside of a Curta I from Rick Furr.
A lot of information came from the Curta Disassembly.

When I had the basics in place I mailed Rick Furr the owner of The Calculator Reference a splendid website with a large section on the Curta with a request for some measurements.
Over the next months I received every measurement I asked for and lots of suggestions too.
Rick measured many of his Curta parts and also sent photographs of all the details.

From then on it was a matter of stepwise refinement

fix a few mistakes
call other mistakes features
add another part or two
think of a new gimmick

and the result is

70 .wrl files with the actual VRML worlds (total: 118 kB)
- 1 main file of 8 kByte
- 69 prototype files between 1 kB and 5 kB each
15 images texture files (total: 227 kB)
- 2 x image texture for settings wheels (hi and lo-resolution)
- 2 x image texture for results wheels adder (hi and lo-resolution)
- 2 x image texture for results wheels turns counter (hi and lo-resolution)
- 1 x image texture for base (bottom) plate
- 1 x image texture for the colar
- 1 x image texture for the indentations in the settings shaft of 12 kB
- 3 x image texture for color settings wheels (3 kB each)
- 1 x image texture for the reversing lever shaft
- 1 x image texture for the body (standard)
- 1 x image texture for the body (with color setters)
12 wave files for the sounds (total: 619 kB)

How Was It Done - The version for X_ITE - 2020

Now that the BS Contact viewer is no longer available for free download it was time to move to another viewer. The X_ITE viewer works with WebGL and works on most modern browsers.
It is free, there is no flying saucer and it doesn't expire.

Best of all there is nothing to download and install.

Thanks and Curta links

Rick Furr

Rick Furr is the owner of The Calculator Reference a splendid website with a large section on the Curta.
He measured a lot of Curta parts, tested the model and mailed a lot of suggestions and photos.

The Posters you can order on his page are a must have for every Curta Collector.

Rien Mol

For my daily reminder that a Curta simulation is a completely pointless exercise.
No better motivation to continue!
Imagine that it was a real project... With meetings, a plan, reviews and a boss...

But to be fair, he certainly had a few perfect suggestions. When I find time...

Nick Yinger

For proof reading everything and finding 28 errors in 8 files.

Curta site of Red Garlic design

Build your own

Over the years I received several mails requesting to use the files of YACS for 3D printing projects.
There are several reasons why the YACS files are NOT a good starting point for a 3D Curta project.

YACS is handcoded VRML and JavaScipt
Much of the VRML is created with JavaScript
Many of the parts that make up the Curta are not present in YACS
The dimensions are from measuring a real Curta
Some dimensions are changed to make it work

The original Engineering Drawings

A full set of the original engineering drawings for the Curta Calculators is available thanks to the curator of the MuseumMura in Mauren, Liechtenstein.

To download the drawings

Go to the site of MuseumMura
In the second row of pictures scroll right to Legendäre Technik with the picture of the Curta
Click the Picture of the Curta
Select Curta Rechenmaschine in the menu bar
On the Curta Rechenmaschine page scroll down to the end
In the box Download ...
You see curta_1_engineering_drawings.zip and a lot more...

Comments and Suggestions

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