On Sun, Feb 21, 2021 at 4:16 AM Victor Stinner <vstinner@python.org> wrote:

There is also a 4th category: platforms/archs which are really not
supported, like they legacy ones for which we removed the code :-)
Examples: BeOS, MacOS 9, platforms with no thread support, etc.
 
FWIW, BeOS may be resurfacing somewhat, with https://en.wikipedia.org/wiki/Haiku_(operating_system) - it's on a second beta now.