The Sharp QT-8B Micro Compet, a portable electronic desktop calculator, was the first mass-produced calculator to be battery-powered. Introduced in mid-1970, it was based on its immediate predecessor, the QT-8D introduced in late 1969, but it replaced the QT-8D's integrated

power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a ...

with a rechargeable

battery pack A battery pack is a set of any number of (preferably) identical batteries or individual battery cells. They may be configured in a series, parallel or a mixture of both to deliver the desired voltage, capacity, or power density. The term battery ...

. It has the same calculating

integrated circuits An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...

as the QT-8D and is of similar appearance and dimensions; the power supply is the only major difference. The QT-8B's release price in Japan was 117,000

yen The is the official currency of Japan. It is the third-most traded currency in the foreign exchange market, after the United States dollar (US$) and the euro. It is also widely used as a third reserve currency after the US dollar and the e ...

. The U.S. price in mid-1971 was $495, equivalent to about $2,700 in 2010. These prices were somewhat higher than those for the preceding QT-8D. The QT-8B's battery pack contains six nickel-cadmium C batteries connected in

series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used in ...

, giving a total

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...

of 7.5

volt The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defin ...

s and, with the original batteries, a total capacity of 1200 milliampere-hours. (Modern nickel-cadmium C batteries have much greater capacity.) For recharging, the calculator accepts 12-volt DC external power, with an input power rating of 6.5

watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...

s. Normally the calculator is recharged from AC power by plugging it into an external charging station (model QTA-2) which is a little longer than the calculator and has a plug that fits into the calculator's charging socket. The calculator sits on top of the base of this charging station and can be used while charging; it can also be locked into the station for extra stability. An adapter for using 12-volt DC automobile power was also available. The display used is

vacuum fluorescent display A vacuum fluorescent display (VFD) is a display device once commonly used on consumer electronics equipment such as video cassette recorders, car radios, and microwave ovens. A VFD operates on the principle of cathodoluminescence, roughly ...

.There is a slight difference between the QT-8D and the QT-8B in the operation of the right-hand display tube, which contains both a minus-sign indicator and a large dot. On the QT-8D, this dot is used as an overflow error indicator. But on the QT-8B, it acts as a low-battery indicator; overflow errors are signalled by displaying all zeroes with all the decimal point indicators lit. Sharp made an

OEM An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...

version of the QT-8B for Burroughs, the Burroughs C3146, which has some significant differences from Sharp's own version. The QT-8B needs an external station for recharging its batteries and for AC operation, but the C3146 has its AC power supply built in, along with the batteries and charging electronics, and can thus be plugged directly into AC power. Since the C3146 has both a battery pack and an AC power supply, it also has a larger case to accommodate them. Like the Sharp, the Burroughs machine can also use 12-volt DC automobile power via an adapter. Otherwise, the C3146's electronics are identical to those of the QT-8B.

References

External links

Sharp QT-8B in Curtamania
(In English) {{Sharp Corporation QT-8B