Abstract: A computer controlled ink jet printing system for printing messages in dot matrix format on objects such as cartons or the like as they move along conveyor lines past printing stations, and which includes one or more print head controls. The system further includes a plurality of print heads, at least one per print station, for discharging ink onto the objects as they move therepast in accordance with a programmed message. Each print head control is capable of controlling print heads at a plurality of stations with the print heads at one station controlled independently of those of another station to print programmed messages at their respective stations. A main controller is linked to each print head control and includes a programmable microprocessor whereby messages may be selected at the main controller for printing by each print head.