A label printing apparatus includes a main frame, a drum housing privotably mounted in the main frame, and a printing drum, mounted in the drum housing, which comprises a plurality of discs each having a series of die groupings about its periphery as well as a groove associated with each die grouping. An assembly for setting each disc to place a selected die grouping in printing position and for simultaneously shifting all of the discs to shift each set die grouping from a first to a second character printing position comprises a spur gear mounted for reciprocation in the direction of the printing drum axis and for rotation to selectively engage each disc and to disengage from all discs. A locking bar, having a notch, is linked to the spur gear to reciprocate with it and position the notch in alignment with the disc engaged by the spur gear. The remainder of the bar projects into a groove in each of all other discs to hold them against rotation during the setting operation. However, the bar is coupled to the drum housing to pivot with it and thus shift the discs during the printing operation. An arrangement for moving a ribbon-type printing medium in operative relation to the printing drum comprises a ribbon cartridge held in the main frame by a mounting bracket. A drive train winds the medium through the cartridge past the printing drum.