I loved writing Z80 assembly back in the 1980s but it was a bit of as shock to find out from Ken Shirriff [1] that this 'number cruncher' had a 4 bit ALU. [1]

I loved writing Z80 assembly back in the 1980s but it was a bit of as shock to find out from Ken Shirriff [1] that this 'number cruncher' had a 4 bit ALU. [1] http://www.righto.com/2013/09/the-z-80-has-4-bit-alu-heres-how-it.html http://www.righto.com/2013/09/the-z-80-has-4-bit-alu-heres-h... EDIT: Just to be clear this is in no way intended to be a criticism of the Z80. On the contrary it's a tribute to the ingenuity of Federico Faggin and Masatoshi Shima that they were looking for ways to 'save' transistors in the ALU in a way which no-one would notice, which presumably enabled them to add more features elsewhere.