Lear Siegler ADM-5  
Written by Accutron on 2017-05-24  

The Lear Siegler ADM-5 is the fourth iteration of the legendary ADM-3 series of terminals, the predominant dumb terminal in use at UC Berkeley's CSE department during the development of Unix. Introduced in May 1975, The ADM-3 was considered a "glass teletype", as it lacked cursor control. The ADM-3 was followed by the ADM-3A in July 1976, the ADM-31 in July 1978, and finally the ADM-5 in January 1981. All four of these terminals share a common form factor, internal construction and basic functionality, while their differences are confined to such secondary characteristics as case color, keyboard layout, DIP switch locations, minor firmware improvements, and the presence or absence of cursor control, lowercase characters and basic graphics support in the default configuration.

One familiar characteristic of the ADM-3 and ADM-3A is the location of its DIP switches, hidden under a removable nameplate positioned to the left of the keyboard. This configuration was abandoned with the ADM-31 and ADM-5, which feature an extended keyboard and DIP switches located on the rear of the unit.

Due to the close association between the ADM-3 and the development of UNIX, various quirks of the terminal live on as characteristics of the C shell and other Unix command shells. Examples of this include: the tilde character as a shorthand notation for the Home directory (tilde and Home were printed on the same key on the ADM-3), the HJKL keys are used for cursor movement in the vi editor (cursor movement arrows were printed on those keys on the ADM-3), and the predominant use of control key combinations more ergonomically appropriate with the ADM-3 control key, which is located above the Shift key.

Lear Siegler ADM-5 dumb terminal.

ADM-5 dumb terminal, logic board.

This article is part of the [Digital Computer Equipment] exhibit.

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