C3195-60101PC Board - Main Logic Board - Includes Integrated RS232-C (Serial) and
C3195-69101PC Board - Main Logic board - Includes integrated RS232-C (Serial) and bi-tronics/centronics (Parallel) interface ports
C6074-69283PC Board - Main Logic PC board DesignJet 1050C 1055CM PLUS Main Logic Board inch A inch VERSION ARE CONNECTORS. (B VERSION has thermistor instead of connector ).