Mathematica 71 bytes
Taking as the range of "printable" characters ASCII 32-126, this takes the complement of the full set of characters (CharacterRange[32, 126]
) and the used set of characters ("Charactes@Rngplm[32,16]"
).
Complement[CharacterRange[32, 126],Characters@"Charactes@Rngplm[32,16]"]
{"!", "#", "%", "^", "&", "*", "(", ")", "_", "-", "+", "=", "~",
"`", "{", "}", "|", "\", "<", ">", ".", ";", "\"", "?", "'", "/",
":", " ", "0", "4", "5", "7", "8", "9", "A", "b", "B", "d", "D", "E",
"f", "F", "G", "H", "i", "I", "j", "J", "k", "K", "L", "M", "N", "o",
"O", "P", "q", "Q", "S", "T", "u", "U", "v", "V", "w", "W", "x", "X",
"y", "Y", "z", "Z", "$"}
0x20
to0x7e
, which are defined as the "printable ASCII characters". Technically tabs and newlines are actually control characters. \$\endgroup\$