Abstract: This disclosure discloses a graphics transmission system using a chalk writing blackboard, a transceiver and a memory. The blackboard is a pressure-sensitive device under control of circuitry in the transceiver producing indicia of the instantaneous position of the chalk on the writing surface. An eraser tray and eraser at its base provide a means to automatically condition the transceiver to interpret a pressure as erase rather than a write command, simply by the absence of the eraser from the tray. Further signal processing yields a more faithful sampling and reproduction of the written signal. A tape recording adjunct is interconnected through a modulation and phase lock loop network that reduces transmission channel and recorder-introduced signal distortion both in the record and the playback modes.