space cadet

Space-cadet keyboard

The Space-cadet keyboard is a device used on MIT Lisp machines and designed by Tom Knight, which inspired several still-current jargon terms in the field of computer science and influenced the design of Emacs. It was inspired by the Knight keyboard (also developed by Tom Knight), which was developed for a sort of predecessor to the Lisp machine OSs — the ITS.

This device was equipped with no fewer than seven modifier keys: four keys for bucky bits ("control", "meta", "hyper", and "super"; the latter two of which were introduced by this keyboard ) and three shift keys, called "shift", "top", and "front". Many keys had three symbols on them: a letter and a symbol on the top, and a Greek letter on the front. For example, the "L" key had an "L" and a two-way arrow on the top, and the Greek letter lambda on the front. By pressing this key with the right hand while playing an appropriate "chord" with the left hand on the shift keys, you could get the following results:

Key pressed Result
L l (lowercase l)
shift-L L (uppercase L)
front-L λ (lowercase lambda)
front-shift-L Λ (uppercase lambda)
top-L (two-way arrow)

Each of these might, in addition, be typed with any combination of the "control", "meta", "hyper", and "super" keys. On this keyboard, it is possible to type over 8,000 different characters. This allowed the user to type very complicated mathematical text, and also to have thousands of single-character commands at their disposal. Many users were actually willing to memorise the command meanings of that many characters if it reduced typing time (this attitude shaped the interface of Emacs). Other users, however, thought that so many bucky bits was overkill, and objected to this design on the grounds that such a keyboard can require three or four hands to operate.


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