Id were using a 3rd party sound library for Doom to handle the nitty-gritty aspects of DOS sound hardware, so the open source release was based on the linux port of Doom. People had to port it back to DOS.
They couldn't release the windows port of Doom either, as that had been done by Microsoft, and would therefore include Microsoft copyrighted code.
With Quake, Id did their own windows port, so it was possible to release the source code for winquake.
They couldn't release the windows port of Doom either, as that had been done by Microsoft, and would therefore include Microsoft copyrighted code.
With Quake, Id did their own windows port, so it was possible to release the source code for winquake.