Abstract: A printing method and apparatus is disclosed wherein the printhead has a linear array of nozzles oriented in an axis, and drops of a liquid are printed at a particular location from first and second nozzles of the printhead at a first location. In an embodiment, the nozzles are arranged in groups, each group of nozzles being used to superpose spots of a particular liquid at a different location. A further method is described wherein the printhead is triggered by transferring printing triggers from a processing module to a printhead at print intervals representative of a plurality of fixed units of spatial displacement of the printhead. The present invention is particularly advantageous for the cycling of print nozzles, superposition of spots in linear arrays and fine control of spot positioning. The invention has particular application in the field of printing DNA microarrays.