Hand-held Calculators

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Busicom LE-100A "handy"
&
NCR 1844

The Busicom handy LE-100A and the NCR 18-44 were Busicom's second series of pocket-sized calculators after the LE-120 series.

Busicom handy LE-100A

Busicom LE-100A “handy”

Busicom handy LE-100A

Distinctive features: Lower-cost development of the first pocket-sized calculator, the Busicom handy LE-120A, using a Texas Instruments "calculator on a chip".

Technical details:
Display is 10 digits red LED.

Four-function.

Integrated circuit - Texas Instruments TMS0106 (here date coded week 11 of 1973).

Batteries - 6v, 4x AA.

67 x 124 x 25 mm (2.6" x 4.9" x 1.0").

Went on sale in September 1972.

Made in Japan by Nippon Calculating Machine Corporation.

This is one of the Busicom "handy" models (the first was the LE-120A) which were the first pocket-sized calculators.
This model uses a Texas Instruments plastic packaged "calculator on a chip" supporting a 10-digit display.  This chip was cheaper than the Mostek ceramic-packaged chip supporting a 12-digit display used in the LE-120A and LE-120S and so resulted in a cheaper calculator. The TI chip also has the much more useful floating decimal point rather than only the fixed decimal point of the Mostek chip.

Busicom LE-100A “handy” On-Off switch

The On-Off switch is on the lower edge of the calculator, with the decimal point setting switch below the keys.

Busicom LE-100A “handy” circuit board.

The electronic components are packed onto two small circuit boards behind the keyboard.  On the upper board above, the black package of the Texas Instruments TMS0106 "calculator on a chip" integrated circuit can be made out on the left, behind the components at the front.

NCR 18-44

NCR 1844

NCR 18-44

Distinctive features: Similar to the Busicom handy LE-100A, shown at the top, which is a lower-cost development of the first pocket-sized calculator, the Busicom handy LE-120A.

Technical details:
Display is 10 digits red LED.

Four-function.

Made in Japan by Nippon Calculating Machine Corporation and badged for National Cash Register of the U.S.A.

The introduction in late 1970/early 1971 of the Mostek MK6010 "calculator on a chip" integrated circuit combined with the use of 7-segment LEDs made it possible to fit all of the electronics of a calculator into a very small space, so producing the first truly pocket-sized calculator, the Busicom handy LE-120A.
Shortly afterwards, Texas Instruments announced that it was developing a "calculator on a chip" too, which was to be the TMS0102.  The LE-100A featured here uses the TMS0106, a slightly later chip for 10-digit displays.

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Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.