Abstract: Disclosed is an improved serial impact printer which both prints and serrates a document. The printer includes a print wheel which is rotated to position a selected character in front of an anvil. The print wheel includes a wheel-like circular member having print characters at the end of fingers which extend from the top of the print wheel's perimeter. An impact mechanism pressures the selected print character against the anvil, the document being positioned between the selected print character and impact mechanism. The impact mechanism includes a d.c. motor which turns a threaded shaft which is engaged with a threaded hole in the end of a hammer. Counterclockwise motion of the d.c. motor advances the hammer's head to pressure the back of the print character against the anvil, thereby printing and serrating the document with the selected character. Thereafter, clockwise motion of the d.c. motor restores the impact mechanism to its original position.