1.2 History

troff can trace its origins back to a formatting program called RUNOFF, written by Jerry Saltzer, which ran on the CTSS (Compatible Time Sharing System, a project of MIT, the Massachusetts Institute of Technology) in the mid-sixties.² The name came from the use of the phrase “run off a document”, meaning to print it out. Bob Morris ported it to the 635 architecture and called the program roff (an abbreviation of runoff). It was rewritten as rf for the PDP-7 (before having Unix), and at the same time (1969), Doug McIlroy rewrote an extended and simplified version of roff in the BCPL programming language.

In 1971, the Unix developers wanted to get a PDP-11, and to justify the cost, proposed the development of a document formatting system for the AT&T patents division. This first formatting program was a reimplementation of McIlroy’s roff, written by J. F. Ossanna.

When they needed a more flexible language, a new version of roff called nroff (“Newer roff”) was written. It had a much more complicated syntax, but provided the basis for all future versions. When they got a Graphic Systems CAT Phototypesetter, Ossanna wrote a version of nroff that would drive it. It was dubbed troff, for “typesetter roff”, although many people have speculated that it actually means “Times roff” because of the use of the Times font family in troff by default. As such, the name troff is pronounced ‘t-roff’ rather than ‘trough’.

With troff came nroff (they were actually the same program except for some ‘#ifdef’s), which was for producing output for line printers and character terminals. It understood everything troff did, and ignored the commands that were not applicable (e.g. font changes).

Since there are several things that cannot be done easily in troff, work on several preprocessors began. These programs would transform certain parts of a document into troff, which made a very natural use of pipes in Unix.

The eqn preprocessor allowed mathematical formulae to be specified in a much simpler and more intuitive manner. tbl is a preprocessor for formatting tables. The refer preprocessor (and the similar program, bib) processes citations in a document according to a bibliographic database.

Unfortunately, Ossanna’s troff was written in PDP-11 assembly language and produced output specifically for the CAT phototypesetter. He rewrote it in C, although it was now 7000 lines of uncommented code and still dependent on the CAT. As the CAT became less common, and was no longer supported by the manufacturer, the need to make it support other devices became a priority. However, before this could be done, Ossanna died by a severe heart attack in a hospital while recovering from a previous one.

So, Brian Kernighan took on the task of rewriting troff. The newly rewritten version produced device independent code that was very easy for postprocessors to read and translate to the appropriate printer codes. Also, this new version of troff (called ditroff for “device independent troff”) had several extensions, which included drawing functions.

Due to the additional abilities of the new version of troff, several new preprocessors appeared. The pic preprocessor provides a wide range of drawing functions. Likewise the ideal preprocessor did the same, although via a much different paradigm. The grap preprocessor took specifications for graphs, but, unlike other preprocessors, produced pic code.

James Clark began work on a GNU implementation of ditroff in early 1989. The first version, groff 0.3.1, was released June 1990. groff included:

• A replacement for ditroff with many extensions.
• The soelim, pic, tbl, and eqn preprocessors.
• Postprocessors for character devices, POSTSCRIPT, TeX DVI, and X Windows. GNU troff also eliminated the need for a separate nroff program with a postprocessor that would produce ASCII output.
• A version of the me macros and an implementation of the man macros.

Also, a front-end was included that could construct the, sometimes painfully long, pipelines required for all the post- and preprocessors.

Development of GNU troff progressed rapidly, and saw the additions of a replacement for refer, an implementation of the ms and mm macros, and a program to deduce how to format a document (grog).

It was declared a stable (i.e. non-beta) package with the release of version 1.04 around November 1991.

Beginning in 1999, groff has new maintainers (the package was an orphan for a few years). As a result, new features and programs like grn, a preprocessor for gremlin images, and an output device to produce HTML and XHTML have been added.