I just bought a box of Apple items and found two mystery cards: One says Heuristics Inc model 2000B copyright 1979 and has an 1/8" phono jack. The other has a bunch of empty sockets (I'm assuming someone pulled various 74LS series chips out of the card) but still has an MC6845P and three chips labelled 'I (U3)', 'II (U28)', and 'III (U17)'.