HyperBBS was written entirely in HyperCard by Harry Chesley. It uses a set of serial port XCMDs developed by me at Apple Computer, Inc.
None of this would have been possible without the work of Bill Atkinson and Dan Winkler, who created HyperCard and HyperTalk. Neither would it have been possible without Apple Computer, which had the foresight to (1) make a truely innovative computer: Macintosh, and (2) produce and effectively give away a truely innovative software product: HyperCard.