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Details:

• A thermal printer provides for physical output on 6mm wide paper.  
  The display is formed by this paper stepping from right to left with each key press.
• The thermal paper being used is provided in easy to change cassettes.
• It contains rechargeable batteries and needs a special dual-outlet charger.  
  Of this charger two versions were available:
  A slow standard charger (Model 10A) and a more expensive fast charger (Model 20A).
• Although it was bought on the German Ebay, my version seems to be aimed at the Japanese market. (See machine bottom)

In the latter half of the 1960s, Texas Instruments initiated the Cal Tech project to develop expertise in the design and production of Large-Scale Integrated (LSI) circuits, targeting the consumer market. As a demonstration of their capabilities, they developed a small, battery-powered handheld calculator.  A “paper display” was selected for this calculator because alternative technologies, such as LEDs, were not yet commercially available, and others, like Nixie tubes, were too large and consumed too much power.

In collaboration with Texas Instruments, Canon created the Pocketronic, utilizing the TI chipset, which included three MOS-LSI chips (TMC1730, TMC1731, and TMC1732), along with the TI thermal printer. While the Pocketronic's construction differs somewhat from the Cal Tech calculator, there are significant similarities, as detailed in the Cal Tech patent for this “miniature electronic calculator.”  (See the  Assets page for a link)

The top-left photo shows a print on the original, probably 50-year-old paper, while the second photo shows a crisp and clear output on recently purchased thermal paper.

With dimensions of approximately 20 x 10 x 5 cm and a weight of 820 grams, it is not truly a pocket calculator. However, it represented a huge step forward in miniaturization.

Because of the historical impact of this calculator, there are numerous publications available on the internet.  

Some can be found via the Assets page.

Usage:

Addition/subtraction:

<1st Number>   + (or -)     <2nd Number>   + (or -)    =

 

Multiplication/division:

<1st  number>     X  (or :)       <2nd number>  =

Note:  Before starting a new calculation  the calculator must be cleared. It’s done by pressing the C-key.
           After a multiplication or division the Clear operation is automatically executed.

At first glance, the use seems similar to today’s calculators.  However, in many details it differs a lot.  For the way it handles minus signs and chain calculations you will need the User Manual.

A link to the User Manual is provided on the assets page.

Click to view a full size picture (opens in a new tab)

Serial number:

Built in:

Functions:

Power:

Market-introduction:

Production until:

Price:

304000

1971  (The top PCB shows a date)

Addition, Subtraction,  Multiplication,  Division

Two NiCd battery packs: 6 x AA  and  7 x 2/3AA

1970 in Japan (source: Electronic Design May 24 1970)

1971  (Advert in a 1971 Dutch newspaper)

1975  (1975/1976 it is replaced by the Pocketronic II )

Fl. 1600,- in 1971  (Dutch advert)