I found a .ps that generates timing wheel patterns (discs with alternating black and white radial bands). you'd plug in inner/outer radius, number of bands, and

I found a .ps that generates timing wheel patterns (discs with alternating black and white radial bands). you'd plug in inner/outer radius, number of bands, and you'd get a printable document from that file. As in, the .ps file was code, which printed as an image. I now know this is the origin of pdf but it blew my mind.