Planet Sinclair

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O Oxford 100 / 200 / 300
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Last updated
8 Jan 1998

Oxford 100 / 200 / 300

The genesis of the Sinclair Oxford was somewhat unusual. In November 1974 Sinclair, along with several other companies, was asked to design a table-top calculator for Gillette, who were at the time tentatively entering the consumer electronics market. Sinclair invested a lot of time and effort in the project but to no avail: Gillette got cold feet and decided instead to put the whole project on hold, nervous about economic and pricing uncertainties. It never did go ahead, at least not with Sinclair on board.

Clive did not let the company's efforts go to waste, however, particularly as Gillette had covered the tooling costs (so in effect, the development was free from Radionics' point of view). In March 1975 the Sinclair Oxford range was launched. The three models all used the same basic case - they could disguished by their "click-action keys" being "colour-coded yellow, blue and avocado":

  • The Oxford 100 (top right) was the calculator originally designed for Gillette. It used a chip brought from General Instruments but which was fundamentally the same as that used in the Cambridge. The machine cost 12.95 + VAT at 15%.

  • The Oxford 200 had the addition of a % key and a memory (a big deal in those days!) for the price of 19.95 + VAT.

  • The Oxford 300 (below right) was a scientific model, which at 29.95 + VAT set a new price level for this type of calculator.

Unfortunately, the gremlins in the Sinclair design studio cropped up yet again, ruining the Oxford's chances of being a genuine pocket (or "briefcase") calculator. The peak current consumption was 40mA, while the batteries' recommended maximum was only 10mA. This tended to drain the batteries very quickly indeed. Computer Digest magazine recommended using the PP9 battery instead:

"It's got the same connections on it and has a recommended range of 5-50mA. So you won't use it up in record time. The other point about the PP9 is that it's 6.6cm x 5.2cm x 8.1cm and weighs close on one pound. So it would have the added advantage of making the Oxfords into genuine desk calculators."

As we'll see, this wasn't the last time that a "kludge" would have to be added to a Sinclair product.

Oxford 100



Oxford 300