I remember my scientist uncle showing me round the UK's National Physical Laboratory in the summer of 1979, aged 13. At one point, to amuse me, he printed out a dot-matrix picture of a scantily clad woman, which seemed to be a familiar image to the (all-male) scientists in the room. It may have been Lenna [1, referenced in TFA], I don't know. But it was undoubtedly the first digital smut I ever saw.