I have degrees in Electrical and Computer Engineering, have designed 4 ALUs and built 3 of those 4. ALUs are interesting, but they're probably one of the most s

I have degrees in Electrical and Computer Engineering, have designed 4 ALUs and built 3 of those 4. ALUs are interesting, but they're probably one of the most simple components of a CPU. Ignoring look ahead aspects and speculative execution, the instruction decoder is probably the most complex part of a CPU, because it has to decide what inputs to use ( whether register or RAM), what part from which to receive output and where to store the result. An ALU is basically a collection of all of your common mathematical operations you'd expect in the CPU. It just takes inputs and a selector and performs the indicated operation. I designed a (unoptimized) MIPS ALU in Verikog in one evening over a bottle of whiskey (minus division related operations).