He has remade a system similar to the core of the great 1970's Xerox Alto / Xerox Star series :-)
I never thought someone would remake a processor this way. I love that kind of madness !
[edit: use the site backup if it fails to load: http://mycpu.thtec.org/www-mycpu-eu/index1.htm ]
https://hackaday.io/projects?tag=CPU (Some are FPGA, most are TTL) Including two risc-v implementations (one seems stalled):
https://hackaday.io/project/18491-worlds-first-32bit-homebre... (No activity for a while now) and https://www.youtube.com/playlist?list=PLEeZWGE3PwbansoxKjjMK...
One I am particularly interested in is the Gigatron:
https://hackaday.io/search?term=Gigatron&category=project%20... (Especially now that there's real IO being hacked in)
Walter gave a talk recently about it: https://www.youtube.com/watch?v=rbaAmnhZAis