Before 1990? Tricky. It was only in the late 1980s and '90s that the PC boom really took off IIRC, with the good years still occurring or ahead of them there's not really any impetus to make any large changes compared to our timeline. There's some options like handling MS-DOS differently but that could come with its own problems, others like buying Apple might end up precluding it from becoming what we know of as Apple.With a POD before 1990 have IBM remain at the top of the computer industry with Apple being just a niche player.
Might that not run into anti-trust problems? Microsoft had to work damn hard to keep from being declared a monopoly and they still eventually had to split off things like Internet Explorer to settle cases. If IBM is selling hardware and the software that their competitors manufacturing compatible and non-compatible PCs essentially have to use then it makes them an even larger target.Isn't the traditional POD that they manage to buy DOS rather than licence it?