IBM has, over the past couple of decades, done their damndest to morph themselves into a Consulting/AI firm, but 40 years ago it was all about moving metal and collecting rent^h^h^h^h selling service contracts for their metal. It's a common latter day assumption that IBM set out to make an open industry standard with the IBM PC. The IBM PC was intended to lock customers in just as much as all of IBM's previous products did. To that end, the BIOS was copyrighted, and IBM included a full listing of the source code in the user manual. IBM's assessment was that, even in the unlikely event someone did manage to reverse-engineer the PC's BIOS, they would be unable to prove (or even credibly claim) that they had done so cleanly. Of course this assessment was proven wrong within two years, but that's another story.