Microsoft's biggest existential risk in the 80s was not having a "real OS"[0]. They had DOS, which they bought from SCP[1] to fix a problem IBM was having, and they had XENIX, which they had to license from AT&T. DOS was technically unsound - it almost sort of worked for personal computing but nobody was going to build workstations out of IBM PCs running DOS. They wanted to build a "real OS" on top of XENIX, going as far as to add porting aids between DOS 2 and XENIX in what they dubbed "XEDOS". Then Bell Labs started selling System V directly in 1983 and Microsoft chickened out of UNIX.
In this environment, Microsoft wound up writing several attempts at home-grown "real OS" projects: Multitasking DOS 4, and ADOS, which then became OS/2. None of these succeeded. OS/2 got close, but Microsoft really didn't like working with IBM, and Windows 3[2] was selling way better. Microsoft ultimately got itself out of this dilemma with NT and Windows 95, both of which used a slightly modified Win32 API that was "real OS" compatible. However, that was almost a decade during which any number of companies could have easily upended, if not killed the company.
BSD didn't start separating itself from AT&T owned code until 1989. Had they done so earlier, Microsoft could have pivoted to a BSD-based XENIX and saved themselves the cost of an AT&T license (which drastically increased with SysV). Microsoft could have shipped Windows on top of that instead of, say, the hackery that was WIN-OS/2 or waiting for Dave Cutler to design and build NT.
[0] Virtual memory, apps run in protected mode ring 3, and preemptive multitasking.
[1] Seattle Computer Products, not the SCP Foundation
[2] Which is not a "real OS" in the sense that it's technically near identical to the Macintosh's system software.
In this environment, Microsoft wound up writing several attempts at home-grown "real OS" projects: Multitasking DOS 4, and ADOS, which then became OS/2. None of these succeeded. OS/2 got close, but Microsoft really didn't like working with IBM, and Windows 3[2] was selling way better. Microsoft ultimately got itself out of this dilemma with NT and Windows 95, both of which used a slightly modified Win32 API that was "real OS" compatible. However, that was almost a decade during which any number of companies could have easily upended, if not killed the company.
BSD didn't start separating itself from AT&T owned code until 1989. Had they done so earlier, Microsoft could have pivoted to a BSD-based XENIX and saved themselves the cost of an AT&T license (which drastically increased with SysV). Microsoft could have shipped Windows on top of that instead of, say, the hackery that was WIN-OS/2 or waiting for Dave Cutler to design and build NT.
[0] Virtual memory, apps run in protected mode ring 3, and preemptive multitasking.
[1] Seattle Computer Products, not the SCP Foundation
[2] Which is not a "real OS" in the sense that it's technically near identical to the Macintosh's system software.