I guess I'll date myself by saying that when I started studying CS, I used ed and thought nothing of writing programming assignments with it. It seemed totally natural. I recall a typical sequence of writing a few lines and then printing out a block of lines to the screen to check. Then jumping somewhere else printing out a block of lines, editing some more etc. I recall hearing about vi and thinking it was overly complex and obviously wouldn't have worked on the hard-copy terminals (really, hard-copy terminals - no screen!) that were scattered about the lab. I don't think I could have conceived of eclipse...