Drum printer

In a drum printer, drum rotates in front of the paper and ribbon. Here characters are imprinted on the paper when print hammers strike the paper. During hammering, characters are imprinted from the drum through the ribbon. The geometry of the drum here is cylindrical with characters embedded around it. One full set of character is attached to each print position. For printing characters, the magnetically driven hammers in each character position strike the paper and ribbon against the spinning drum. Geometry is adjusted in such a way that one complete line of characters is printed during each rotation of the drum. The main disadvantages of this system are difficulty in changing the fonts and wavy kind of printing lines.