I'm pondering about building CPU from logic gate chips. The thing is most projects like that use chip count efficient (usually microcoded) designs which aren't fast enough to run "real" familiar software. I want 32-bit instruction set with virtual memory, capable of running Linux and fast enough to run games like Doom. Fastest reasonably available logic gate family is 74AUC (possibly with exception of exotic ECL gates). Combined with copious use of fast asynchronous SRAM chips, I think performance in the ballpark of 20 MIPS should be attainable. I'm half-expecting that I'm making some huge error in my assumptions and it will turn out these numbers are impossible, but that didn't happen yet.