Fun fact: Before microprocessors were invented, there was already ALU chips, like the 74181 ALU chip, that were used in CPU boards. [https://www.righto.com/2017/01/die-photos-and-reverse-engineering.html Source ]
And creating a 16-bit ALU was just a matter of combining four 74181 ALU chips with a 74182 carry lookahead carry chip. [http://www.6502.org/users/dieter/a7/a7_3.htm Source]
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