The space-cadet keyboard is a keyboard designed by John L. Kulp in 1978 and used on Lisp machines at Massachusetts Institute of Technology (MIT),[2][3][4] which inspired several still-current jargon terms[citation needed] in the field of computer science and influenced the design of Emacs.
This allowed the user to type very complicated mathematical text, and also to have thousands of single-character commands at their disposal.
[7] Other users, however, thought that so many keys were excessive and objected to this design on the grounds that such a keyboard can be difficult to operate.
[5] Emacs uses "M-" as the prefix for ⎇ Alt when describing key presses: the "M-" stood for Meta on the space-cadet keyboard, and when Emacs was ported to PCs, the Alt key was used in place of Meta.
It also included four Roman Numeral keys (I, II, III, and IV) which allowed for easy interaction with lists of four or fewer choices.