Knight (TK) keyboard

This keyboard was used with the MIT-AI lab's bitmapped display system.

Some interesting things to note about this keyboard:

Ctrl and Meta are right next to one another.
The Rubout key is right to the left of the home row, making correcting input immensely easier than a modern keyboard's BS key in the upper right.
The Top key and the SAIL character set on the tops of the alphabetic keys.
The Esc key was used to control the terminal system itself.
The Alt key, separate from Esc, was used as the prefix for operating system (DDT) commands.
An unshifted colon key was used to introduce long DDT commands.
The Call key was used to interrupt a program and return to DDT (^Z in ASCII mode). Being positioned in the upper-right, it allowed for quite satisfying (if futile) banging on the key when a program was stuck in a tight loop.
The Backnext key was used for things like terminal linking. Because of the way the metal was positioned, this key makes a different thunk from all the other keys.