CTSS roff is a descendant of the
RUNOFF program by
Jerry Saltzer, which ran on
CTSS.
Douglas McIlroy and
Robert Morris wrote runoff for
Multics in
BCPL based on Saltzer's program written in
MAD assembler. Their program in turn was "transliterated" by
Ken Thompson into
PDP-7 assembler language for his early Unix operating system, circa 1970. When the first
PDP-11 was acquired for Unix in late 1970, the justification cited to management for the funding required was that it was to be used as a
word processing system, and so
roff was quickly transliterated again, into PDP-11 assembly, in 1971.
roff printed the
man pages for
Versions 1 to
3 of Unix, and when the
Bell Labs patent department began using it, it became the first Unix application with an outside client.
Dennis Ritchie noted that the ability to rapidly modify
roff (because it was locally written software) to provide special features was an important factor in leading to the adoption of Unix by the patent department to fill its word processing needs. This in turn gave Unix enough credibility inside Bell Labs to secure the funding to purchase one of the first PDP-11/45s produced. ==See also==