‘IBM PC Compatible’: How Adversarial Interoperability Saved PCs From Monopolization

Electronic Frontier Foundation

Adversarial interoperability is what happens when someone makes a new product or service that works with a dominant product or service, against the wishes of the dominant business.

Though there are examples of adversarial interoperability going back to early phonograms and even before, the computer industry has always especially relied on adversarial interoperability to keep markets competitive and innovative. This used to be especially true for personal computers.

From 1969 to 1982, IBM was locked in battle with the US Department of Justice over whether it had a monopoly over mainframe computers; but even before the DOJ dropped the suit in 1982, the computing market had moved on, with mainframes dwindling in importance and personal computers rising to take their place.

The PC revolution owes much to Intel’s 8080 chip, a cheap processor that originally found a market in embedded controllers but eventually became the basis for early personal computers, often built by hobbyists. As Intel progressed to 16-bit chips like the 8086 and 8088, multiple manufacturers entered the market, creating a whole ecosystem of Intel-based personal computers.

In theory, all of these computers could run MS-DOS, the Microsoft operating system adapted from 86-DOS, which it acquired from Seattle Computer Products, but, in practice, getting MS-DOS to run on a given computer required quite a bit of tweaking, thanks to differences in controllers and other components.

When a computer company created a new system and wanted to make sure it could run MS-DOS, Microsoft would refer the manufacturer to Phoenix Software (now Phoenix Technologies), Microsoft’s preferred integration partner, where a young software-hardware wizard named Tom Jennings (creator of the pioneering networked BBS software FidoNet) would work with Microsoft’s MS-DOS source code to create a custom build of MS-DOS that would run on the new system.

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