[pickle-wizard]

Windows NT was originally going to be OS/2 NT. Due to the architecture of NT, it could support many different APIs.

Due to the success of Windows 3.0 and the lack of OS/2 success, Microsoft wisely decided to expand the Windows API to the Win32 API and have it be the default API.

The book Show Stopper, has a good account of the early days of NT.

https://www.amazon.com/Show-Stopper-Breakneck-Generation-Mic...

It is interesting read.

[sedatk]

Original NT contained an OS/2 subsystem layer too, like WSL today. It allowed running of OS/2 1.x apps.

[temac]

WSL is vastly different from the old-school NT subsystems. Both in the technology and in the result. And rightly so, because while SFU&co was in some way more integrated, it effectively was a separate platform from anything else, and who want to support that? Arguably the OS/2 subsystem did not have this problem because the environment/ecosystem to support was way smaller, and it was making existing binaries made for this system work. So on that last point, yes WSL is similar to the OS/2 subsystem; but it could not have been like that in SFU because Linux was not seen as a serious competitor at the time (and well, it actually was not...); and the price to pay now that co-evolution did not happen is a more segregated environment.