High density dot matrix printer

Abstract

A high density dot matrix printer is disclosed which can print characters with variable font and having print resolution close to that of a typewriter. Printing on both a forward and reverse pass of a line of characters with the dot print head coupled with offsetting the dot matrix print head for the reverse pass printing doubles the line density in printing characters to increase resolution. In addition, a compacted character code arrangement is utilized having a different printing code for the reverse pass printing than for the forward pass printing, and uses single binary words to represent many dot printing positions dependent on the location of the single binary word in the character code coupled with using single binary words to represent many possible dot positions in which no dots are to be printed. This compacted character code arrangement permits the use of a relatively small amount of memory and results in operating a larger number of print head pins in printing each character than heretofore practiced in the art to greatly increase print resolution. A lower level of increased resolution printing is obtained by utilizing the compacted character code technique for the forward pass printing but deleting reverse pass printing to increase printing speed when required.