An archive video explaining how the National Semiconductor Datachecker scanning system, and more importantly, UPC scanning in general, worked when new in 1974.
The cash register has the same design as other Datachecker registers of the era, just with an alphanumeric display along the top. I remember a variation used by the Tops chain back then, but they had numeric segmented displays in the main register housing, instead of a separate display along the top.
The dot matrix printer and receipt format are pretty much the same as used by later NS/Datachecker systems in the late 1980s.
The video lives here:
Here’s some photos of the non scanning variation.6_4D_200