SuperPaint, one of the earliest computer graphics systems. The UI above, the hardware below. Found these while looking up history on primitive pixel drawing. Check out this little story from that page:
In the earliest days of SuperPaint, the runcode hardware wasn’t yet working, so all paint brushes were one pixel wide (and any height)! Artist Fritz Fisher had taken a job as a night guard at our building in order to be near the system, and images like this one often greeted us in the mornings. When Fritz wasn’t guarding or painting, he read Gravitation by Misner, Wheeler, and Thorne to pass the time.
That seems like a guy worth tracking down.