> The 68000 had address adders, separate from the ALU. It actually had a 16 bit "complex ALU" and two 16 bit adders (or the other way around - I can't get to m

> The 68000 had address adders, separate from the ALU. It actually had a 16 bit "complex ALU" and two 16 bit adders (or the other way around - I can't get to my old documents in my office). The ALU was for the D registers, one of the adders was for the A registers and the last one could be shared for both to add bits 16 to 31. You could do a one cycle addition of an address in parallel with a one cycle ALU operation on 16 bits of a data register (very common) or two cycles for 32 bits. You could also do a 32 bit add on a data register in a single cycle if you were not also calculating an address. So you could crunch 48 bits per clock.