David Butleradded August 28, 2020

This is the Pulsar Time Computer Model 901. It is an LED watch and wrist calculator from 1976.
The time and date are displayed via the big pulsar button. The calculator is activated via pressing the "0" key followed by the "C" key. Mine appears to be working, and i have an original Pulsar stylus and pen known the the "command pen". Internally, it uses four button cell batteries.
The later Pulsar 902 looks almost identical, though the "R" and "S", as well as the "=" and "C" keys have swapped positions. However, the 902 adds a way to display time by flicking your wrist, as well as a day-of-the-week feature.