Linux Device Drivers, Second Edition

NuBus

Another interesting but forgotten interface bus is NuBus. It is found on older Mac computers (those with the M68k family of CPUs).

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 file drivers/nubus/nubus.c includes almost everything we know about this bus, and it’s interesting reading; it shows how much hard reverse engineering developers had to do.