Xenix, DOS, Word

Microsoft—initially named Micro-Soft—released Xenix, a version of UNIX, prior to releasing MS-DOS. Neither operating system was developed by Microsoft, instead being licensed (Xenix) and purchased outright (MS-DOS).

The first version of Microsoft Word was released for Xenix. It was originally known as Multi-Tool Word for Xenix systems. Like many of their flagship products, it too was not created by Microsoft, having been created at Xerox PARC (now simply called PARC).

On a related note, most of the core developments in computing considered important today were either developed at, or emerged from, a small handful of companies, research laboratories, and universities, among them Xerox PARC, AT&T Bell Labs, MIT, Berkeley, Stanford, and Carnegie Mellon.