Zilog Z80 turns 50 as an open-source replacement heads to drop-in DIP40 silicon. GitHub is here, they do announce have a run on 180nm at wafer.space (Tim Ansell's reaction to the demise of eFabless).
I've hoped that those open PDKs and associated silicon projects would enable recreation of vintage chips eventually, and at last it is happening for real
I've hoped that those open PDKs and associated silicon projects would enable recreation of vintage chips eventually, and at last it is happening for real