The IBM 4704 (further details here) uses application-specific buckling spring keyboards of relatively unique layouts. This page details the examples that I’ve come across personally.

Note that although the image above shows a 77-key (for comparative purposes), I do not own a 77-key. That image was sourced from Geekhack.org years ago.

All 4704 keyboards connect directly to the 4704 terminal base unit using a cable fixed to the keyboard, with a DE connector with 4 populated pins. These keyboards are not readily usable with anything other than a 4704 terminal, however conversion projects exist and have made excellent progress.

Part Number 6019284

The 62-key keyboard for the IBM 4704 is likely the most in-demand among hobbyists for its layout and size attributes. It is the only known “60%” capacitive buckling spring keyboard originally sourced from IBM, and projects exist to try to build modern clones of it. I obtained it in May 2011 after considerable research and discussion with other enthusiasts. It is solely responsible for prompting my documentation of the 4704 which in turn prompted a tremendous increase in their market value (for better or for worse).

This keyboard has been nicknamed “Kishsaver” by a subset of the Geekhack IRC community on account of me introducing them to it.

Identification: IBM part number 6019284, ID number 472X-41-13?, designated ‘Model 200’, manufactured in USA by IBM 45-1983
Application: IBM 4704
Connectivity: DE, 4 populated pins, fixed cable, 4704-unique protocol
Key layout: 62-key 4704 alphanumeric layout
Keyswitches: tactile and ‘clicky’ buckling spring over capacitive PCB
Acquired: May 2011, commercial sale online

Part Number 6020218

The 107-key keyboard is the largest available for for the 4704. Layout-wise, and based on when it was introduced, it is a step between the beam spring terminal keyboard layouts of the 1970s and the 104/122 key layouts of the 1980s and later.

This tends to suggest the engineering/design work that went into its layout may have inspired the 101-key enhanced layout of the original Model M, and which we continue using today with few alterations.

Identification: IBM part number 6020218, ID number 472X-41-49383, designated ‘Model 400’, manufactured in USA by IBM 29-1987
Application: IBM 4704
Connectivity: DE, 4 populated pins, fixed cable, 4704-unique protocol
Key layout: 107-key 4704 administrative layout
Keyswitches: tactile and ‘clicky’ buckling spring over capacitive PCB
Acquired: February 2013, commercial sale online (sold March 2018)

Part Number 6019273

Note: this part number is suspected not to be accurate.

The 50-key keyboard for the IBM 4704 is the only grid/matrix-layout capacitive buckling spring keyboard which I am aware of. It is one of the earliest (if not the original) application to use transparent keycaps for custom-printed legends.

Identification: IBM part number 6019273 (as sold; cannot be confirmed due to bottom sticker being absent)
Application: IBM 4704
Connectivity: DE, 4 populated pins, fixed cable, 4704-unique protocol
Key layout: 50-key 4704 function grid layout
Keyswitches: tactile and ‘clicky’ buckling spring over capacitive PCB
Acquired: February 2013, commercial sale online