Thursday, January 19, 2012

Sinclair Executive Pocket Calculator - it all adds up!

We have recently been donated this original Sinclair Executive handheld calculator. This is one of the earliest electronic pocket calculators that can claim to actually be pocket sized - the New Scientist Journal reviewed it as 'the first calculator that can comfortably fit in the user's pocket along with his wallet and cheque book'. It was a third thinner than anything else on the market when it was launched in August 1972. 

Sinclair Executive Calculator with Texas Insturments GLS 1802 chip inside. Dimensions: 138mm(H), 56mm (W), 9mm (D).
The significance to Bedford is the fact that the tiny silicon chip, known as the 'Calculator On' chip, that operated the display and components for the calculator was invented and manufactured by Texas Instruments in Bedford. Texas Instruments had moved and expanded from Dallas, USA to Bedford, UK in 1957 to built one of the largest semi-conductor research and manufacturing facilities, to assist their expansion into the European markets.
The miniature silicon integrated circuit chips were developed for a range of applications, the pocket calculator being just one. I am sure many of our readers will have owned or come across Texas Instrument calculators, computers and other devices available during the 1970's and 1980's. Other products aside from the calculator that used the 'microcomputer' chip, invented in 1971 by Michael Cochran and Gary Boone, included microwave ovens, sewing machines, telephones, vending machines and of course early electronic computer games.

Texas Instruments Offices built at Dallas Road, Bedford in 1958 © Texas Instruments Ltd. 
Sinclair Radionics Ltd. was a firm based at Huntingdon and the inventor of the pocket calculator was Clive Sinclair. Clive wanted the calculator to be truly pocket sized and designed it to use button cell (watch type) batteries, rather than the standard AA size batteries to allow the calculator to be much thinner. He also experimented with the TI chip, using it in a new way that allowed the cell batteries to last much longer through pulsing the power to the chip.   

John, our donor, bought the calculator soon after it was launched while he was working at the Sunlife for Canada insurance company in Northampton. He remembers seeing it advertised in the Daily Telegraph on the train on his way down to London to the Ideal Home Exhibition at Olympia, where his company had a stand. The calculator was advertised from the recommended retail price of £84 at the discounted price of £59. He decided that he would purchase one for his work and thinks it was bought from a shop either in Oxford Street or Tottenham Court Road. John remembers that at first he would forget to turn off the calculator when not in use to preserve the batteries, which did not last long – only around 2 hours. John bought the calculator for use by himself and others in his team – who he trained to use the equipment. It requires 4 button cell batteries and these became expensive and difficult to get hold of, so John stopped using the calculator after about 4 or 5 years. The calculator still has its red velvet case, instructions for operation and manufacturers details. It is certainly a valued addition to our collection as a contemporary item connected with Bedfordshire's technological development and industry.

If you think that you have an iconic Texas Instrument's object that you know was made or developed in Bedford along these lines then feel free to share it with us in the comments, on facebook, twitter, or get in touch via 

Lydia Saul
Keeper of Social History

Thanks to our donor, John.
Thanks to Kenneth Sanders for the photograph of the Texas Instruments building.
For further information see Texas Instruments Timeline
For further information about Sinclair Executive Calculators see Vintage Calculators website

1 comment:

  1. Even the legendary super-brain Isaac Newton was known to complain about the time it took to do simple sums on paper. So this invention has been a big help and a wonderful innovation.