Abstract: A chart recorder useful in a marine depth sounder or in other applications. Chart paper for the recorder is loaded into a paper cartridge, which is insertable in the recorder. The paper cartridge supports a roll of chart paper, a takeup spindle for winding the paper, and a viewing surface across which the paper travels after data marks are recorded on the paper. An internally-driven roller within the recorder frictionally engages the takeup spindle when the cartridge is in place, so as to move the chart paper at a selected linear speed. The drive roll is operated by an electric motor and a multiple-stage compound reduction gear arrangement, all entirely contained within the drive roller.The paper marking stylus of the recorder makes full-time contact with a stylus engaging surface throughout each revolution of the stylus drive belt. An inductive sensing device is located between sides of the drive belt, and senses a magnet carried on the outside of the belt.