BASIC

In the book '''Invisible Engines,''' three authors develop of a theory of how software platforms can be two-sided (or multi-sided) in the sense of two-sided markets, where, for instance, both buyers and sellers must come together for profits to be made. Microsoft's Windows operating system is one example of a two-sided platform. On one side, computers need an operating system to function, so hardware manufactuers such as Dell purchase licenses to Windows and pass along the costs to consumers. On the other side, computers are only valuable if there are applications written for them. Microsoft writes some of the applications for Windows, but third-party developers write many. The abundance of software encourages users to stay with Windows.

Of course, Windows was not the first two-sided platform -- it was not even Microsoft's first. By retaining the rights to what IBM called PC-DOS, Microsoft had previously been able to license MS-DOS to other companies, much as they would later sell OEM copies of Windows to them. And before that, there are continuities with the company's first product line, Microsoft BASIC. While BASIC was a language, not an operating system, the presence of BASIC allowed for programs to be written on a computer and sometimes sold. And, computers in the late 1970s and early 1980s needed BASIC on them seem full-featured, so different computer manufacturers were eager to license the language from Microsoft. At Gates's and Allen's company, the success of BASIC and the essential business plan used there helped to develop the later success of MS-DOS and Windows.