"I remember getting my hands on the first beta of
Windows NT, starting up the POSIX subsystem and trying some code
out on it. It was a joke. Networking? That's not part of the
official POSIX spec, so no access to the network. Windowing? That's
not in there either, so no fancy graphical interfaces for your
POSIX programs, pure text based code only. Anything not fully
mandated by the spec was ripped out. Yes, it could pass the pure
POSIX conformance tests, but that was all it was able to do. No
useful code could run on this system, as all of it expected
something more than the basic standard, which most other POSIX
vendors had managed to create de-facto standards around. The
Windows subsystem even had some of these de-facto POSIX-like
standards (the Berkeley sockets networking interface for example)
but these were explicitly excluded from the Windows NT POSIX
subsystem. The only purpose was to allow government purchasers to
check the box marked "POSIX compliant" but allow them to purchase
completely proprietary Windows solutions, and that's just what they
did. It implemented the letter of the law, whilst completely
ignoring the spirit of it. "