You never forget your first UNIX. 
Since everyone else seems to be, I might as well....
BSD 4.1c on a VAX-11/750, very shortly afterwards replaced by 4.2.
But my first taste of Unix was prereleases of Eunice.  My larval phase
was spent under VMS on an 11/780, and Eunice was terribly, terribly
confusing until I found out what it was resembling.
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