A couple of low level Z80 projects by Andras Tantos

Two linked blog posts may be of interest: the resurrection of an Enterprise 128 by designing new ROM and RAM expansions, and the development of a T80 vs Z80 comparator board, aiming for enough cycle accuracy to work in an Amstrad PCW 8256

Enterprise 128: a blast from the past | Modular Circuits

Shadow Tracer: the road to perfection | Modular Circuits