Oh, how soon we forget. LED watches seem to be all the rage recently, with a sudden flood available in the sub-$100 range. Let's take a quick look at another market segment that died a quick death in the mid 1970s. Pulsar was first out of the gate with an LED calculator watch in 1975, followed in 1976 by models from Compuchron (above), Uranus, and even HP.
The strangest of all was the 1977 Wrist Calculator from Sinclair (right) -- it didn't include a built-in watch. Apparently, you were supposed to lug it around on your wrist while searching for people in need of emergency arithmetic.
Like their watch-only brothers, these little counting machines chewed through batteries so quickly that the display could remain on for only a few seconds at a time. The Compuchron's boxy metal housing hides four largish button cell batteries that provide the electrons for its careful pondering.
Lets hope some enterprising Chinese firm isn't gearing up to churn out remakes of these - it was bad enought the first time. They're occasionally available on the second-hand market as "new old stock" -- the technology developed so quickly that many units were left unsold.
Vintage Calculators (Web Museum with zillions of pictures)