Originally Posted by vinea
He didn't need to. He already had a vision of selling his OS to multiple manufacturers which is why he retained the rights to do so.
Which is why when Microsoft was first approached by Toshiba to do one, Microsoft said no. Full and legal compatibility was the key. Companies like Columbia and Eagle which tried to simply copy IBM's code were hauled into court, where they lost. Does illegal copying count as first-ness? I don't think so.
The real breakthrough was from Compaq. They were the first to figure out how to reverse engineer the ROM-BIOS without violating IBM's copyrights. Phoenix was next, and arguably more important, since they sold their ROM-BIOS chips to all takers.
The simple fact remains that IBM had every intention of retaining control of the PC hardware platform, which is why it didn't matter to them if Microsoft retained the rights to DOS. They even widely published their BIOS code and made copies available for free, in order to make it more difficult to find programmers who could attest in writing that they'd never seen it. It's easy to claim today, with the benefit of perfect hindsight, that reverse engineering the BIOS was obvious. Clearly it wasn't so obvious then, because IBM planned on retaining control that way. And it required a large investment of time and money from Compaq to work around IBM's roadblocks, so it was hardly a trivial exercise.
As I've already said, IBM's handling of the development of the PC from the start was a blunder, which they compounded over time. They tried to get it done all too quickly (for IBM, anyway) and failed to take the project as seriously as they should have done, or would have done if they'd really understood the desktop computer market. The PC was conceived as a rear-guard action to protect what they regarded as their real business, the big iron.
The point is, nobody anticipated the legal cloning of the IBM-PC, or its impact, until after it was happening. It was the ability of dozens of companies to crank out hardware that could be called "IBM compatible" without actually being from IBM that legitimized the PC industry. It was a quirk of history -- an important quirk, and one that benefited Microsoft hugely. But it was not someone's plan.
As for the effects of this on the evolution of the industry, that's a matter of opinion. Mine is that it was very harmful, that a more natural progression involving competition between platforms would have advanced the technology more quickly. I believe this, because this is precisely how progress is made in every other industry we could possibly mention, and I don't see computers as being some great exception to the rule. If you're going to argue that something is so completely exceptional, then you need a pretty exceptional set of supporting facts to back it up. Simply saying, in effect, "because it happened that way" is not enough.
Sources: Gates, by Manes & Andrews; Hard Drive, by Wallace & Erickson; Accidental Empires, by Cringely.