TRAC (Text Reckoning And Compiling) is an interpreted, interactive, ultra-light-weight programming language, in use since 1964. TRAC T64 was developed between 1959-1964 by Calvin N. Mooers. His goal was to develop a language that could be operated interactively from the keyboard of a "reactive typewriter." Growing from his earlier work on information retrieval systems, Mooers originally envisioned TRAC as a tool that could be used by librarians and others in their everyday work. TRAC T64 was first implemented on a PDP-10 in 1964 by L. Peter Deutsch. It was used until 1984, when Mooers redefined the language in its current version. A specification for a new version is being created, to be released with an open source license.