In 1972, Hewlett Packard came out with the HP-35 - the radical idea of a calculator small enough it could slip into your shirt pocket.
My father, a physicist, bought one immediately. On returning home to London from a trip to the States, he pulled out the promised presents and then this ungainly calculator, which was black and blocky with tiny stiff keys.
Nevertheless, his enthusiasm was palpable, and it wasn't just that he could throw away his slide rule. The clunky number cruncher was a revolution in portable computing - even if it did cost $395 (more than $1,700 today).
Like so many ideas that have spun out of America's history of ingenuity, the boxy little calculator set a new course. "Inventing America: A History of the United States," by four writers, looks at the well-trodden sweep of America's story but gives it a fresh twist by highlighting the technological triumphs (see review).
Although pocket calculators, batteryless and as slim as a credit card, are given away free today, their popularity was a surprise in the early days. According to HP, a market research firm told the company that the new compact calculator would never sell. It was too small, the firm said.
Bill Packard decided to push ahead anyway, and HP has never looked back.
In an age when nano-technology and the miniturization of everything are huge driving forces behind research, "too small" now seems wildly absurd.
So watch out, the next new thing may already be sitting on your desk, looking curious and out of place - but ready to break the mold.