Best keyboards you've used ever! - test-drb@ccmp.vtda.org

31 Aug 2004

...
 From: ard(a)p850ug1.demon.co.uk

Brent> Speaking of various keyboards: some time ago I received a bare
  Brent> (no machine, no case, no ID) keyboard utilising
  Brent> magnetically-activated reed relays for the key contacts. Reed
  Brent> relays were commonly used for calculator keyboards in the
  Brent> late-60s/early 70s and it probably dates from this era, but
  Brent> this is the only occasion I have seen reed relays used in an
  Brent> alphabetic keyboard.

 Tektronix also used this. The Tek 4014 has such a keyboard. 
Maybe we should make a list of the various keyboard technologies : 

Mecahnical switches 
  Metal contacts pressed together by key
  'Snap action' domes or strips (e.g. HP35)
  Membranes pressed together when key is pressed
  Metal contacts held apart and allowed to touch when key is pressed 
  (e.g. VT100)
  Microswitches
  Reed switches

Hall Effect sensors

Capacitance change devices
  Plastic flap over PCB (e.g. IBM PC)
  'Keytronics' type

Transformer coupling between PCB tracks -- moving core on the key 
(e.g. ICL Termiprinter)

Pair of balanced transformers, one of which is damped by the key (e.g HP9810)

Mecahnical encoding, parallel output mechanical contacts (e.g. ASR33)

Mechanical encoding, serial output mechanical contact (e.g. Creed 7E)

What have I missed (I think I have examples of all of those in use here!)

-tony
 Hi
 You missed acoustic delay line.
Dwight