Abstract: The printer is mounted on a desk-top computer and can print both numeric characters and graphic and calculation symbols in two different colors. The characters and the symbols are provided in a relief configuration in accordance with a matrix of rows and columns on a rubber sheet wrapped around a rotatable drum. The characters in adjacent columns are inked by an inking roller formed by adjacent porous discs which are alternately impregnated with red and black ink. The drum can perform a translatory movement in the axial direction selectively to present to the printing hammers the columns of characters which are linked with black and the columns of characters which are linked with red. The drum is translated fixedly with respect to the inking roller by means of a cam which rotates at a speed half the speed of the drum and engaged with one or other of two cam follower pins which can be selected by means of a solenoid.