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Sharp QT-8B "micro Compet"

Sharp QT-8B

Sharp QT-8B "micro Compet"

Distinctive features: One of the first hand-held, battery powered calculators.

Technical details:
Display is 8 digits, green vacuum fluorescent "Itron" tubes.

Four-function.

Semiconductors, describing the identical chipset in the Sharp QT-8D: "Has four MOS/LSI chips and a clock generator. Each chip contains 900 MOS transistor equivalents." (Electronic Design, Jan. 1971).
"The logic tasks are split up among the four packages. The first, called the NRD 2256, handles the display and numerical read-in functions. Decimal-point control is taken care of by the second circuit, the DC 2266. The third, AU 2276, handles digital addition and register input control. The fourth the AC 2266, rides herd on the arithmetic and provides the registers." (Electronics, March 1969).

7.5v (6x C NiCd rechargeable cells), charging unit provides 12v input.

The calculator alone is 245 x 132 x 70 mm. (9.6" x 5.2" x 2.75").

Was being advertised by June 1970.

Cost in U.S.A. in June 1971 US$495[1].

Made in Japan.

By replacing the AC power supply circuitry of its QT-8D with rechargeable cells Sharp produced this model, the world's first battery-powered electronic calculator.

To recharge the batteries the calculator is docked into a charging unit, shown on the right.

The display uses stylised "Itron" vacuum fluorescent tubes, with half-height zero, here showing 12345670.

In recharger
With recharger

The QT-8B alongside the charging unit.

Inside

With cover removed, showing the two circuit boards, display, and rechargeable battery compartment.

Circuit board

The four Rockwell integrated circuits on the lower board, with the display board above holding 8 "Itron" numerical display tubes and one "Itron" sign/error display tube.

Batteries

On the left is the battery pack which holds six size C  rechargeable cells.

On the right is the display tube assembly.

Rear panel

The rear panel with the plug which accepts 12v DC from the charging unit.

In hand

The Sharp QT-8B and the Sanyo ICC-0081 Mini Calculator appear to have reached the market at about the same time in 1970 and were the world's first hand-held calculators, though due to their size they are not "pocket calculators".

Sharp was at the forefront of calculator development and this machine was the start of a long line of hand-held calculators, which gradually became smaller; see the Sharp EL-8, EL-811, and EL-801.

For further information about Sharp Corporation and its calculators visit the Calculator Companies section of this site.

 

References

  1. "Microelectronics Shrinks the Calculator", Popular Science, June 1971, p74.

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© Text & photographs copyright Nigel Tout   2000-2015 except where noted otherwise.