CPU - Basic control unit design
Search for Ben Eater, "Building an 8 bit breadboard computer" on YouTube. He has an entire tutorial on building an 8 bit computer, using 74LS series ICs, on a breadboard.  He is currently working on the Control Logic including the instructions and micro-code.  This is an awesome tutorial that takes you through every module of a working computer capable of running simple programs. He starts with the basics of each module and develops a working unit that is clear and easy to understand.  Can't recommend it enough!!!  Hopes this helps