There is a lot of documentation about the Alto. Are there also complete circuit diagrams? I am just curious because the processor was made in TTL at a time before the 6502 and Z80 were born.

Sooner or later the last functional Xerox Alto will cease to work (sadly). In that case it could make sense to replace the dysfunctional parts with modern retro circuits. I wonder if a project to build a functional Alto clone (with TFT as screen) would make less effort than the famous monster 6502 which was presented recently.