IBM Model F
Buckling Spring Keyboard
IBM developed the Model F capacitive buckling spring switch for production in 1981. Its most prominent use was in the IBM PC 5150 keyboards at the time. Lauded as having better 'feel' than the Model M keyboards, they eradicate the need for a rubber membrane underneath the switches, and instead just have the switch 'foot' touching against two contact pads.
The Model F switches are extremely light to the touch, and not as heavy as Model M switches. As such, not everyone immediately prefers them if they are more accustomed to heavier switches. They also generally have excessive spring sound and clatter-- moreso than early Model Ms. The sound is a huge problem for those who like superior keyboards without the sound; whereas others prefer the sound will most likely prefer these keyboards.
122 Model F Software & Downloads
--> 122 Model F to Teensy Pinout
--> Soarer's Converter 1.12 Documentation
--> Soarer's Converter 1.12 Files
--> Teensy Flashing Application
Model F Variants
Here's a list of all major Model Fs:
XT Model F (PN: ?)
AT Model F (PN: ?)
122 Terminal Model F (PN: 611034x)
3290 Model F (PN: 1387033)
4980 Model F (PN: ?)
Displaywriter Model F (PN: ?)
Additional Notes:
The 3290 Model F keyboards are considered as a "space saving" 122 Terminal in that they lack the numpad.
The Terminal 122 Model F keyboards can be modded with a USB controller to be used on any modern computer.
Differences Between Models
Generally all Model Fs seem to be consistent that I've tried. The original PC 5150 Model F is probably the 'crispest' due to the fact it is the most compact version. The Model F spacebar is notorious for being rather odd; Model M users will find it a bit alienating if they're not used to it.