Changes

Note: The uncommon shape of the housing dates back to a Schneider BTX modul (which was being intended to be plugged into Schneider Television Sets). Apparently Schneider produced too many housings, and re-used them for the RS232 interface. Actually, a RS232 interface is very much the same as a BTX interface (the actual BTX modem must be rented separately from Deutsche Bundespost), so even the PCB may be (almost/exactly?) the same for both devices.