Tuesday, 29 January 2013

Transistors - and Moore's Law

Back to science and engineering after a diversion to use of English yesterday – that’s a hostage to fortune so I’d better check this entry carefully!

Looking at GPS reminded me of the underlying technology and how that has changed. I can remember making radios with Red Spot transistors back in the ’50s. These were the first semiconductor devices available to hobbyists. They cost 10 shillings (50p) but that was a lot of money back then. Transistors were used as elements of construction – the original Transistor Radios had these soldered onto the circuit boards. I made one in the early sixties.

The Sixties brought the concept of integrated circuits where complete units – amplifiers or logic gates – were fabricated on a single integrated silicon chip. I can remember using nand gates which had four logic circuits built into a single unit. 

That was the start of an amazing escalation of components on a single chip. My mobile phone probably has nearly one billion (1,000,000,000) transistors! Moore’s law states that the transistor count in circuits doubles every two years. There’s a graph and list of transistor counts in various circuits on the Wikipedia page here.

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