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by grishka 667 days ago
Lithography masks for early integrated circuits were drawn by hand iirc.
1 comments

Not just ICs, microprocessors:

https://en.wikipedia.org/wiki/Rubylith

> Certain digital image editing programs that have masking features may use a red overlay to designate masked areas, mimicking the use of actual Rubylith film.

Oh so that's why masking mode in Photoshop is a red overlay?! TIL.