They produce about as good code as can be produced for any 8-bit (accumulator size) processor (there are some 16-bit instructions for some registers). The PDP-1

They produce about as good code as can be produced for any 8-bit (accumulator size) processor (there are some 16-bit instructions for some registers). The PDP-11, for which C was designed, has a 16-bit register architecture for all registers.