Hand-held Calculators

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Canon Pocketronic & Monroe 10

Two very early hand-held calculators from the same stable, with output printed on thermal paper tape.

Canon Pocketronic

Canon Pocketronic Canon Pocketronic in hand

Canon Pocketronic

Distinctive features: One of the first hand-held, battery-powered calculators. No display, printout on thermal paper tape.

Technical details:
Display is by printout on thermal paper tape.


Main integrated circuits - Texas Instruments TMC1730B, TMC1731A, & TMC1732A (here date coded weeks 18 and 19 of 1971).

15.6v (13x NiCd rechargeable cells).

100 mm x 208 mm x 48 mm (4" x 8.2" x 1.9").

Introduced in Japan in Spring 1970[1], and the USA in early 1971[2].

Made in Japan.

Texas Instruments started to investigate the design of a hand-held calculator in 1966 with the "Caltech" project. This calculator was the resulting commercial product, manufactured by Canon. Texas Instruments was awarded U.S. and Japanese patents for a "Miniature Electronic Calculator".

Like the Texas Instruments Caltech the output is printed on thermal paper tape, manufactured by 3M[2].

Canon Pocketronic

Calculator with the thermal tape cartridge removed and a new, sealed cartridge.

Inside Canon Pocketronic

The base of the calculator with covers opened showing the 13 rechargeable cells which are squeezed in.

Inside Canon Pocketronic

Beneath the keyboard showing the printing mechanism and electronics.

Inside Canon Pocketronic

Beneath the keyboard with the printer circuit board removed to reveal the 3 calculating integrated circuits.

Close up of the Texas Instruments TMC1730B, TMC1731A, & TMC1732A integrated circuits, in ceramic packages.

When introduced in 1970 these calculators were at the cutting edge of technology and still having teething troubles. This is illustrated by a news story in the magazine Electronics in January 1971[3]:

"TI production woes delay calculator
Canon's pocket calculator, which was to be selling in the U.S. last month, is being delayed because production of its thermal print head by Texas Instruments is two months behind schedule. The calculator, called Pocketronic is designed around three MOS circuits and can add, subtract, multiply, and divide; it was to sell for less than $400.
    TI's James W. Clifton, manager of display products, says he expects to catch up during the second quarter. The print head, which is used with thermally sensitive paper to provide hard copy readout, is a silicon array of small dots that can be heated in various combinations to form numbers and other characters. Clifton attributes the delay to the fast turnaround time initially scheduled for the project: 15 months from laboratory to the large-scale production required by the Japanese firm. The Canon calculator also uses three of TI's MOS/LSI circuits. Apparently, there is no problem in delivering these circuits."


A year or two later Texas Instruments started producing its own range of calculators and sold calculator ICs to many other manufacturers.

Monroe 10

Monroe 10

Monroe 10, aka "Shrimp"

Distinctive features: Restyled Pocketronic labelled by Canon for Monroe, a well-established U.S.A. calculator manufacturer.

Technical details:
Main integrated circuits - Texas Instruments TMC1730, TMC1731, & TMC1732 (here date coded weeks 41 and 43 of 1970).

103 x 219 x 43 mm (4.1" x 8.6" x 1.7").

Monroe10 Ad

Advertisement from 1971 for the Monroe 10, here called the "Shrimp".

The cost was "only" US$379.00 (about GBP 160).
According to the U.S. Inflation Calculator the equivalent cost in 2014 would be about US$2,200!

These models were among the first hand-held calculators.

Although they are hand-holdable they are not really "pocket" calculators due to their great length and thickness (208 mm / 8.2" by 48 mm / 1.9").

It is notable that at this point in the development of calculator electronics that three large-scale integrated circuits (LSI) were required for the calculating functions.




  1. Dentaku Museum site at http://www.dentaku-museum.com/.
  2. "Pocket model", Electronics, Apr. 27 1970.
  3. "TI production woes delay calculator", Electronics, Jan. 4 1971, p17.
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Sanyo CX-1
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Slide Rule
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