World’s First Single Chip Scientific Calculator

Sir Clive Sinclair tells a good yarn about how his company came up with the world’s first single-chip scientific calculator.

Sinclair was the UK’s leading electronics entrepreneur in the 1960s, 70s and 80s, pioneering the trail for a host of start-up electronics companies from Acorn to ARM to the mega-cluster of entrepreneurial activity thriving in Cambridge today.

Sinclair’s companies brought out a string of innovative products from pocket transistor radios, to hi-fi gear, pocket TVs, one of the earliest digital watches and pocket calculators, and a sub-£100 personal computer which became the largest selling computer in the US. Sinclair’s story about the first single-chip scientific calculator takes place in 1972. “We did it by taking an existing TI chip which was a four function calculator chip”, recalls Sinclair, “TI had made it internally programmable – you could change the ROM – but it had only three registers.” “We re-programmed that, much to TI’s amazement, to create a full scientific calculator.”

“A friend of mine, Nigel Searle, a computer scientist, did the programming, and I did the algorithms because no algorithms existed at that time which would have worked in just three registers.”

“We went to Texas, stayed in a hotel room, and did the whole job in a few days. We took the programme into TI, then went back and collected the chip.” “TI were completely baffled by this”, remembers Sinclair, “there was a chap at London University, a professor who specialised in algorithms, and he couldn’t figure out how it could ever be done in just three registers. He thought it was technically impossible.”



  1. See attached URL for intersting UK history of first single chip calculator and potentially first microprocessor (or microcontroller).

  2. I had a Cambridge calculator in the 1970’s which used reverse Polish entry- no-one asked to borrow it after the fist try!

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