Sinclair Cambridge
Close-up of a Cambridge
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| Manufacturer | Sinclair Radionics |
|---|---|
| Introduced | 1973 |
| Predecessor | Sinclair Executive |
| Cost | GB£43.95 |
| Calculator | |
| Display type | Light-emitting diode |
| Display size | 8 digit |
| Programming | |
| Other | |
| Power supply | 4xAAA batteries |
| Dimensions | 50 by 111 by 28 millimetres (2.0 in × 4.4 in × 1.1 in) |
The Sinclair Cambridge was a pocket-sized calculator introduced in August 1973 by Sinclair Radionics. It was available both as kit form kit to be assembled by the purchaser, or assembled prior to purchase. The range ultimately comprised seven models, the original "four-function" Cambridge, which carried out the four basic mathematical functions of addition, subtraction, multiplication, and division, being followed by the Cambridge Scientific, Cambridge Memory, two versions of Cambridge Memory %, Cambridge Scientific Programmable and Cambridge Universal.
The Cambridge had been preceded by the Sinclair Executive, Sinclair's first pocket calculator, in September 1972. At the time the Executive was smaller and noticeably thinner than any of its competitors, at 56 by 138 by 9 millimetres (2.20 in × 5.43 in × 0.35 in), fitting easily into a shirt pocket.
A major factor in the Cambridge's success was its low price; the Cambridge was launched in August 1973, selling for GB£32.95 (GB£29.95 + VAT) fully assembled or GB£27.45 (GB£24.95 + VAT) as a kit. An extensive manual explained how to calculate functions such as trigonometry, n-th root extraction and compound interest on the device.
The Cambridge was extremely small for a calculator of the time: it weighed less than 3.5 ounces (99 g) and its size was 50 by 111 by 28 millimetres (2.0 in × 4.4 in × 1.1 in). Power was supplied by four AAA batteries.
The use of cheap components was an important contributor to the unit's cost. A common failure mode was with the switch contacts, making it impossible to switch the calculator off. Due to the use of switch contacts made of nickel coated with tin, rather than the gold, an oxide layer would be smeared across the insulating barrier after repeatedly using the switch.
Numbers were displayed on the 8-digit LED display (made by National Semiconductor) in scientific format with a 5-digit mantissa and a 2-digit exponent. The Cambridge used light-emitting diodes for its display. On later scientific variants the power draw for the display required a larger PP3 battery, creating a bulge in the lower rear casing of the appliance.
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