That's an interesting anecdote. But that still isn't an antitrust violation.
You need market power in order to restrain trade. Otherwise, you're just fantasizing about seizing control of a market without actually having the power to do so. For example, if you and I get together and divided the smartphone market 50/50 between the two of us, that would simply be laughable, not anti-competitive.
But if you do have market power, then your actions could actually be anti-competitive. If IBM had reached an agreement with, say, DEC to split the mainframe and minicomputer market between them, then that would have been an "unreasonable restraint of trade."
But Microsoft held 0% of the operating system market in 1980. In fact, in 1980, Microsoft had market power only in BASIC interpreters. As long as Microsoft didn't try to tie BASIC interpreters to some other product, it would've been very hard for Microsoft to violate antitrust law, even if it tried.
> Your ad hominem on The Register (El Rag as I like to call it) doesn't address the fact that the source of the story is in fact John Wharton, and he has IIRC publicly discussed it elsewhere.
An ad hominem is when someone claims that an argument is false simply because it originated from a certain source. That's not what I did. I attacked the Register after addressing the argument directly. That's not an ad hominem, that's just an attack on the Register.
P.S. Since the information came from John Wharton, it would be best if we could see what he actually said. Right now, Googling for "John Wharton IBM Microsoft Intel" gives only three relevant hits: two articles in the Register, and your original comment.