Or considering they became such a large company selling a product that targeted IBM compatible systems. In that case, they were a consumer of what was essentially an API, but one wonders whether Microsoft would be in the position it is in today if IBM had been able to prevent Compaq and other vendors from creating clean-room implementations of what was essentially the IBM PC API.

IBM would have been in a much better position to push OS/2 and supplant Microsoft's OS offerings if it would have had a monopoly on the PC's supporting it's PC interface.