"This 'Calculator' is actually the Hong Kong version of the 'Magic-Brain' Calculator.
I am very interested in learning how the 'Magic-Brain' calculator came to be made in
Asia. One of the key features of the 'Magic Brain' is the fourplastic clips on the side 
to hold the stylus.  The clip on the side was, of course, used by Addiator but used a 
esign of a single clip made of curved metal.  Where did this four plastic clip 
development come from?
The US made 'Baby' calculators were all metal  until the 50's when they switched to 
a plastic (Bakelite?) back with a painted tin plate riveted to it.  These did not have the
 four clip design (the stylus was attached to the leather carrying pouch by a loop.  
Did 'Baby' develop the 'riveted to plastic' design? Or did they borrow it from elsewhere?
If you have any of these answers or any other information about the historical shift of 
Troncet production from US/Europe to Asia, I would love to hear it.
June 25, 2004 

"Your questions are related to a small segment of newer slide adders. "Troncet type" would not be the best expression because there have been some slide adders before: PERRAULT about 1666 (!!) was the first. KUMMER about 1850 (first production in quantity) So I'd agree to "Perrault type" or simply "Slide Adder" (German: "Zahlenschieber")

All that mentioned slide adders are very simple and without a grid or spring element indside (unlike to Addiator or Produx etc.). Back side is of plastic, front of tin, conneted by 6 rivets. As I know this type was constructed as an simplified and very cheap answer to success of Addiator in USA, end of 1950th. So all those are supposed to be from 1950th until 1970th?

In my collection are: Baby Calculator (USA) 8/9 digits Calculator (Japan) 6/7 digits Chadwick Magic-Brain Calculator (Japan) 7/8 digits Kokometer (USA) 8/8 digits Magic-Brain Calculator (Japan) 7/8 digits OM (Otto Meuter; Germany) 1950th 8/9 digits PIC German Calculator (West Germany) 8/9 digits Taschenrechner (Japan) 6/7 digits Taschenrechner (Japan) 7/8 digits Tom Thumb (USA) 8/9 digits W (W in in rhombus) (Country=?) 8/9 digits

I guess, production was only in Japan or Hong Kong, even though some calcs are marked as "USA" or "Germany".

Above mentioned Baby Calculator has a predecessor with same name, but complete case out of tin (as usual before WW2). This slide adder is from the 1940th, probably some production in 1950th (as I know). There are a lot of other slide adders very similar to that (USA and Europe).

A big problem is to get knowledge of production year. Only this way we can evaluate dependencies. I hope US colleagues can explain more.

Best regards,"

Friedrich Diestelkamp 
Bavaria / Germany

July 1, 2004

Photo: Courtesy of Enrico Tedeshi

Source: The International Association of Calculator Collectors

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