one of Sinclair's most bizarre products, the
strange-looking Wrist Calculator (above right)
was launched in February 1977. It was the
first product of Science of Cambridge, the
company which came between Sinclair Radionics and
Sinclair Research. In some ways it was well ahead
of its time. I'm wearing a Casio calculator watch
at the moment, a development perhaps anticipated
by Sinclair nearly 20 years ago.
The Wrist Calculator, however,
was assembled by in-house designer John Pemberton
out of redundant calculator chips and displays,
mounted on a little PCB with half a dozen of the
smallest cells available to power it. The result
was described rather uncharitably as "an
eyesore in black plastic".
Amazingly, it actually came in
kit form (below right) and (as might be
expected) was a nightmare to assemble. It was
extraordinarily tricky to assemble and, once
completed, there was only a fair to middling
chance of it working. John Pemberton recalled
that it was designed to 'minimal tolerances',
which meant that only if you were lucky enough to
get a set of parts all of which were at or below
the mean size of the prototype's components could
you get it to fit within the case.
Even so, more than 10,000 of the
things were sold to hobbyists from all parts of
the world for a revenue in excess of £50,000.
Another 20,000 were exported to the United
States. The gloss was somewhat taken off this
success when, a few months later, they were all