Mask size or fabrication geometry size? I'm guessing you mean the latter. It depends on the generation of these chips (moving to a smaller process) but I know

Mask size or fabrication geometry size? I'm guessing you mean the latter. It depends on the generation of these chips (moving to a smaller process) but I know the 6502 used a 10 um process at introduction, and I think the 8080 used a 5 or 6 um process. Don't know about the Z80. For comparison, the 80386 was fabricated with a 1um process.