IBM’s Micro Channel Architecture.
Actually, MCA was a pretty good design, but what killed it was primarily IBM's ridiculous licensing fees, which really limited the availability of 3rd party adapters, though the incompatibility with legacy, ISA adapters didn't help. In fact, 1 of the 2 companies that actually licensed and sold computers equipped with the MCA bus produced a "dual bus" server, featuring both ISA and MCA busses (I believe this was before EISA).
For bonus points, what were those 2 companies that actually produced and sold MCA computers, besides IBM?
Mark