Also of interest, posted here a couple of years ago:

ATX-80 – ZX-80 computer clone with ATmega8 processor https://news.ycombinator.com/item?id=29569523

This is not an exact replica like the one linked above, but an ingenious DIY re-creation built with modern parts, including just two ICs, with an ATMega8 processor instead of a Z80. Not an emulation, but a complete rewrite of the original Z80 monitor and BASIC interpreter in AVR assembly.