Who was a rival(?) for Windows NT?

Showstopper를 읽다가...

NT would still meet the goals closest to Cutler's heart: portaility, reliability and the ability to provide an alternative to Unix, the splintered high-end operating program.
This last goal was crucial to Cutler. "Unix is like Cutler's lifelong foe," said one team member who'd worked with Cutler for nearly two decades. "it's like his Moriarty[Sherlock Homes's nemesis]. He thinks Unix is a junk operation program designed by a committee of Ph.D.s. There's never been on mind behind the whole thing, and it shows. So he's always been out to get Unix. But this is the first time he's had the chance.
[Showstopper. 95page]

*Showstopper는 Windows NT가 만들어진 과정을 소설로 꾸민책입니다. 실제 당시 개발자들의 실명을 거론하고 있으며 개개인에 대한 Background까지도 상세히 설명하고 있어 읽는이들에게 흥미 불러 일으킵니다. (단 개발자 분들이 기대하는 것과는 달리 실제 Code적인 내용을 다뤄지지 않습니다)