NCR 4940

Overview

This keyboard was OEMed for NCR(National Cash Register Company)

The external appearance of the NCR 4940. The keyboard was OEMed by NMB and many other companies as well. The keyboard is a terminal-based keyboard therefore, it speaks two different protocols. One of the protocols is AT-based. This protocol has been used to make a converter see the Protocol section.

The keyboard’s layout is unique to this keyboard and is only found on another version of this keyboard that is commonly found under the NCR branding known as the ADDS ASCII:

Switches
Keycaps
Upper Case
Mounting Plate
PCB
Back Plate
Cable

Switches

Keycaps

The keycaps are made out of PBT with dye-sublimated legends. The keycaps for the ADDS ASCII include clips on the sides of the keycaps to secure them properly to the switch. These caps are

Bottom of Keycap

Upper Case

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 upper case in the NCR 4940 does not include the clear plastic strip for custom functions but instead is filled in.

Lower 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 joins the two halves together. The feet that are integrated into the lower case are flush with the lower case when retracted.

Switch Plate

The switch plate is made out of stamped steel. The plate has deeper stamping around the switches so that the entire switch plate could be produced with less material. The plate is only coated with a clear coat.

PCB

The PCB is a double-sided PCB with all traces on the backside of the PCB. The controllers found on the PCB vary, some later models have been found with both Toshiba and Mitsubishi controllers.

Cable

The cable is approximately 1 meter long for the coiled variant and stretches up to 2 meters easily. It contains a molded 5 pin din connector with 6 pin headers using a molex connector on the PCB.