/ˈspeɪs kædət ˈkiːbɔːrd/
n. "Baroque MIT Lisp-machine keyboard with enough modifier keys to make EMACS feel physically possible."
The Space-Cadet Keyboard is a now-legendary keyboard designed for MIT Lisp machines that became famous for its extreme number of modifier keys and symbols, directly influencing hacker jargon and the keybinding culture of EMACS. It evolved from the earlier Knight keyboard and was used on Lisp machines from systems like Symbolics and LMI, where dense, symbol-heavy, Lisp-centric editing was the norm.
Key characteristics of the Space-Cadet Keyboard include: seven modifier (“shift”) keys—four “bucky-bit” modifiers (Control, Meta, Super, Hyper) plus three shift-like keys (Shift, Top, Front) arranged for easy chording; keycaps with up to three legends each (e.g., a Latin letter and symbol on the top plus a Greek letter on the front); the ability to type thousands of distinct characters and single-keystroke commands via combinations of these modifiers. This design encouraged users to memorize vast sets of chords, helping shape the dense, modifier-heavy command style associated with EMACS and classic Lisp environments.
Conceptual example of Space-Cadet-style key use:
Example key legends (top/front) and chords:
G key:
Top: "G" + ↑
Front: γ (gamma)
L key:
Top: "L" + ⇄ (two-way arrow)
Front: λ (lambda)
Sample chords:
Front + L → λ
Front + Shift + L → Λ
Top + L → ⇄
Control + Meta + λ → complex editor command
Control + Meta + Super + Hyper + X → extreme "quadruple-bucky" commandConceptually, the Space-Cadet Keyboard turns the keyboard into a chorded instrument: one hand plays combinations of modifiers while the other taps symbol-rich keys, yielding an enormous command and character space without leaving home row. This excess of “bucky bits” birthed jokes about needing three or four hands, but also made it possible for Lisp hackers to treat the editor and environment—especially EMACS—as a highly tuned, keyboard-driven interface for code, math, and symbolic manipulation.