Dieter Muller has an amazingly interesting collection of interesting ideas about building homebrew cpus with TTL logic. I’m sure to old school logic designers, most of these are old hat, but to the nearly crazed home experimenter, they are quite illuminating. His hints on ALU design are what brought me to the site, so I’m leaving this breadcrumb on my blog so I can find it again easily.
Even more interesting than TTL (to me) is his MT15, the core of which is implemented with discrete transistors and diodes.