BravoX was "modeless", as was Gypsy. While Bravo (and BravoX) were originally implemented in BCPL for the Xerox Alto, BravoX was later re-implemented in a language called "Butte" ("a Butte is a small Mesa", as Charles Simonyi used to say). Alto BCPL compiled into Data General Nova machine instructions, which were in turn interpreted by Alto microcode. Butte compiled into Butte-specific byte codes, which were interpreted by special Alto microcode, similar to the Mesa bytecode interpreter. EDIT command Early versions of Bravo had a command interface designed such that a user attempting to enter the command "EDIT" in command-mode would instead irreversibly replace all text with a "T". The "e" was interpreted to select everything. The "d" would delete everything selected. The "i" would switch back to input-mode with the "t" appearing as the only text. Only one action could be undone, so only the insertion of the t could be reversed. References Further reading External links Bravo Course Outline Xerox Document System Reference Manual Alto User's Handbook. (Bravo is described in pages 27–59.) Word processors Xerox