[kabdib]

There were a number of microkernel efforts at Apple in the 80s and 90s.

- Pink (later known as the money-burning party Taligent) had a 'new kernel' that was message-passing. They spent a lot of time working on RPC efficiency.

- The Newton used a message-passing kernel. Not the most efficient thing in the world, but there was MMU support to do some interesting page sharing / fault dispatch policy stuff, so you could get IPC-like behavior with faults. Basically hobbled by a 20Mhz processor with minimal cache, and not very much RAM at all.

Btw, I didn't notice the Newton being very hard to debug (except that all of our debugging was printf, or you stared at the disassembled output of CFront).