Patent US 4,137,425

The teleprinter is provided with a bialphabetic keyboard, for example latin and arabic, and a dot printing head controlled by two different character generating units corresponding to the two alphabets. The teleprinter is normally predisposed for one of the two alphabets and can be switched to the other alphabet by means of a sequence of characters. The arabic character generating unit is adapted to recognize predetermined sequences for generating composite characters, i.e. the lam-alef group. Furthermore, some characters at the end of a word are generated by adding a tail to the normal character in response to the spacing code. The teleprinter can be connected to the conventional existing teleprinters, since neither the composite characters, nor the tails are transmitted on the line.