The 68000 has three separate 16 bit ALUs: one for DataLow, one for AddressLow and another for AdressHigh. DataHigh can be processed by either the first or the second one. The first one implements all operations while the other two only do add/subtract and some limited shifting.
See figure 8 of: https://www.computer.org/csdl/mags/co/1979/02/01658617.pdf So the 68000 can process 48 bits at a time, but nobody every called it a 48 bit architecture :-) Many official Motorola documents and articles did call it a 16 bit processor, but others said it was a 32 bit one. Certainly the Motorola engineers I dealt with in 1982 always considered it a 32 bit architecture and Apple was hardly the only one to use that term in its marketing material (see Atari, Commodore, Sun, etc). -- Jecel
