I bought a set of "VINTAGE NATIONAL SEMICONDUCTOR FILM PHOTO ETCHES" off ebay. It looks like they are overhead projector transparencies for a class. I scanned them and loaded them as layers into a GIMP file
It turns out they are pictures of the various die masks for the National Semi DM7880C 7-segment decoder/driver. It is similar to the 7447 BCD-to-Seven-Segment Decoder Driver, except the DM7880 uses a 112-bit ROM to hold the segment data, while the 7447 uses logic gates.
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