[david-given]

That's just the microkernel, though --- it didn't contain any functionality other than sending messages (and a few other things, microkernels very).

Fuzix' 27kB contains the scheduler, drivers, tty, file system and Posix subsystem!

[cbsmith]

Fuzix definitely was end to end. On the other hand, the QNX kernel is a more capable foundation to build on.