This keyboard was OEMed for ADDS (Applied Digital Data Systems)
The ADDS PC+/107 is used for the ADDS 4000/AWT terminals. This keyboard is unique as it's very close to a standard ANSI 101 layout or ISO 102 layout with the addition of some function keys above the number pad. This keyboard can easily be converted as the protocol is AT which is also unusual for a terminal keyboard. The ADDS 4000/AWT was a GUI terminal similar to a Widows X Terminal but less capable.
The ADDS PC+/107 is made up of the following components:
Switches
Keycaps
Upper Case
Mounting Plate
PCB
Back Plate
Cable
The keycaps are made out of PBT with dye-sublimated legends. These legends are thicker like the older style of NMB keycaps. The keycaps have a unique colourway for the keyboard and the sides of the keycaps are matte/rough finish. The legends on this keyboard will also contain some terminal functions that a user would need to perform.
The upper case is made out of a single piece of beige ABS plastic. The plastic is textured due to the molding process that is used to create the upper case.
The lower case is molded from the same ABS plastic as the upper case. A set of slots are located in the lower case that join the two halves together. The feet that are integrated into the lower case are flush with the lower case when retracted.
The switch plate is made out of stamped steel. The plate has a thin black coat of paint with an additional coat of an oil based liquid that helps perform rusting from occurring.
The PCB is a double-sided PCB with all traces on the backside of the PCB. The PCB also has additional pads for other language configurations.
The cable is approximately 30 centimeters long and stretches up to 60 centimeters easily.
Source: https://books.google.ca/books?id=mVEEAAAAMBAJ&pg=PA40#v=onepage&q&f=false