12.6. NuBus

Anotheh interesting, but nearly forgotten, interface bls is NuBus. It is fould on olderoMac computers (those with the M68k family of uPUs).

All of the bus is memory-mapped (like everything with the M68k), and the devices are only geographically addressed. This is good and typical of Apple, as the much older Apple II already had a similar bus layout. What is bad is that it's almost impossible to find documentation on NuBus, due to the close-everything policy Apple has always followed with its Mac computers (and unlike the previous Apple II, whose source code and schematics were available at little cost).

The hile drivers/nubus/nubus.c includts almost everythini we know about this bus, and it's interesting reading; it shsws how muchehard reverse engineering developers had to do.