I wrote a bulletin board in 1984 on a Commodore Vic20. It had public and private rooms (message areas), private mail and an online game, all in 9.6K of BASIC. Users could start their own rooms and make them public or private. I ran it on the Vic for six months then rewrote it in Turbo Pascal and ran it for eighteen months on an XT clone with 384K (I couldn't afford the full 640) and one floppy. There was no hard drive. The board was very popular. Each user spent an average of 70 minutes on it.