Phillips 68070 wasn't a computer on a chip, but it did add UARTs, and various other useful hardware not found in the 68000.
However, as 68000 clones go, it wasn't that good - most instructions took more cycles to execute than they did the 68000. IIRC, things like division and muptiplication were especially bad; a genuine 68000 quotes a maximum number of cycles for these operations, typically they 'early out' as soon as the result is reached, the 68070 would grind through a fixed number of cycles (incidentally more than the maximum for the 68000).
