IIRC, Compaq (remember them?) managed to come up with a clean-room PC BIOS clone, which started that whole ball rolling. Then, after IBM tried to re-establish c

IIRC, Compaq (remember them?) managed to come up with a clean-room PC BIOS clone, which started that whole ball rolling. Then, after IBM tried to re-establish control with the MCA (which folks pretty much immediately started trying to work around in various nefarious ways), Compaq also came up with EISA, which kind of blew that out of the water. In fact, IBM's original decision to work with mostly off-the-shelf parts in designing their PC (instead of home-grown stuff) pretty much came back to bite them here, but they were still in the PC/server business for quite a long time. As for their other hardware, these days they're pretty much the only game in town for mainframe and midrange systems. And they jealously guard those markets, as lethargic as these may currently be.