A Multitasking GUI, Circa 1982

autospa points out a post (with video) showing off the multi-tasking abilities of the Blit terminal, developed in 1982 by Rob Pike and Bart Locanthi. Before Windows, before X, and before the Mac (but somewhat later than the Xerox Alto), the Blit terminal provided a multitasking, mouse-driven graphical interface; it took a Unix server on the other side to do the heavy lifting, though.