alt Hacker NewsThe "obviousness" about NT's design I was talking about, compared to the DOS-based Windows versions, were things like a trusted computing base, access control, kernel/user separation, memory protection, etc (stuff the DOS-based Windows versions had little to none of).
POSIX systems have that stuff, too.
In other words, POSIX and NT are both "traditional OS" architectures where the OS serves as a relatively heavy and thick abstraction layer that isolates userspace from the hardware, while DOS-based ("hosted DOS"?) Windows is really more like a thin bare-metal hypervisor which arbitrates or virtualises direct hardware access between VMs running DOS. From that perspective, what users think of as "Windows", i.e. the GUI and the whole Win32 environment, is actually just another DOS application running in the protected-mode environment of a DOS extender (DPMI).