The unfortunate reality of building these home-brew CPUs is that almost all of the "medium integration" ICs are long out of production - things like the 74181 ALU slice, carry lookahead adders, 16-way register files, etc.
Makes doing things larger than 8/16 bit computers very complicated and usually very slow :(
Makes doing things larger than 8/16 bit computers very complicated and usually very slow :(