extensions out of that. Joy used a Lear Siegler ADM-3A terminal. On this terminal, the Escape key was at the location now occupied by the Tab key on the widely used IBM PC keyboard (on the left side of the alphabetic part of the keyboard, one row above the middle row). This made it a convenient choice for switching vi modes. Also, the keys h,j,k,l served double duty as cursor movement keys and were inscribed with arrows, which is why vi uses them in that way. The ADM-3A had no other cursor keys. Joy explained that the terse, single character commands and the ability to type ahead of the display were a result of the slow 300 baud modem he used when developing the software and that he wanted to be productive when the screen was painting slower than he could think. Distribution Joy was responsible for creating the first BSD Unix release in March, 1978, and included ex 1.1 (dated 1 February 1978) in the distribution, thereby exposing his editor to an audience beyond UC Berkeley. From that release of BSD Unix onwards, the only editors that came with the Unix system were ed and ex. In a 1984 interview, Joy attributed much of the success of vi to the fact that it was bundled for free, whereas other editors, such as Emacs, could cost hundreds of dollars. Eventually it was observed that most ex users were spending all their time in visual mode, and thus in ex 2.0 (released as part of Second Berkeley Software Distribution in May, 1979), Joy created vi as a hard link to ex, such that when invoked as vi, ex would automatically start up in its visual mode. Thus, vi is not the evolution of ex, vi is ex. Joy described ex 2.0 (vi) as a very large program, barely able to fit in the memory of a PDP-11/70, thus although vi may be regarded as a small, lightweight, program today, it was not seen that way early in its history. By version 3.1, shipped with 3BSD in December 1979, the full version of vi was no longer able to fit in the memory of a PDP-11; the editor would be also too big to run on PC/IX for the IBM PC in 1984. Joy continued to be lead developer for vi until version 2.7 in June 1979, and made occasional contributions to