A terminal unit (10) comprising a base unit (11), in turn including a main body (17) and a scanning device (16) located in front of the main body (17), and a printing unit (12), distinct from the base unit (11), in which the scanning device (16) has a width (L1) greater than that of the main body (17) so that it has a lateral portion (16c) protruding from the latter, and also ìn which the base unit (11) has a seat (21), defined by one edge (11 e) of the main body (17) and by the protruding portion (16c) of the scanning device (16), so as to removably accommodate the printing unit (12) beside the base unit (11) and behind the scanning device (16). The terminal unit (10), in the configuration with base unit (11) and printer (12) side by side, presents a clearance (L4) in the transverse direction that is significantly lower than the sum of the transverse clearances (L1, L3) of the scanning device (16) and of the printer (12), and in particular is within preestablished limits, so that the terminal unit (10) can be used to advantage to replace existing terminals quickly and easily.