Abstract: A data system includes a portable printer unit and a portable data collection terminal. The printer unit and the data collection terminal are communicatively coupled by a data link which may be a low power radio frequency data link, or it may be a standard communications cable. The portable printer unit is distinguished over other portable printers by, among other features, having the capability of printing a check routing data block in magnetic ink and in a manner which conforms to MICR (Magnetic Ink Character Recognition) standards. Coding and decoding of data may be provided based on printer unit or printer cartridge specific data which may be transmitted from the printer unit to the data collection terminal. The portable printer unit is also adapted to receive a paper supply from either a roll paper supply cartridge or a sheet paper supply cartridge, having the capability to distinguish between the two types of cartridges.