Sinclair Cambridge

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 , fitting easily into a shirt pocket. A major factor in the Cambridge's success was its low price; when launched in August 1973, it sold for ( + VAT) fully assembled or ( + VAT) as a kit. An extensive manual explained how to calculate functions such as trigonometry, nth root extraction and compound interest on the device. In October 1974, according to a newspaper advertisement, the type 3 could be bought in the United Kingdom by mail order for £16.95 (including VAT & Post & Packing). == Design ==

The Cambridge was extremely small for a calculator of the time: The use of cheap components was an important contributor to the unit's cost. A common defect was failure of the switch contacts, making it impossible to switch the calculator off. Due to the use of contacts made of nickel coated with tin, rather than gold, an oxide layer would be smeared across the insulating barrier after repeatedly using the switch. 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. == Variants ==

A later model, the Sinclair Cambridge Scientific, was launched in March 1974 at a price of £49.95 (£5 cheaper than its nearest rival from Hewlett-Packard). As the name suggests, it was a development of the Cambridge, using the same case, with the addition of some common scientific functions (sin, cos, tan, etc.).) was released in 1975. It lacked accuracy in many of its scientific functions, some yielding only four significant digits. It featured a single memory register and a limit of 36 program steps, along with a conditional jump instruction. The Cambridge Programmable was superseded by the Sinclair Enterprise, which allowed 80 program steps. == Emulator ==

Veniamin Ilmer transcribed the ROM of the chip die from the Sinclair Cambridge Type 2, and in 2024 built an emulator using it. == References ==