question.pl

          s/\x00/␀/g; # seems like 00 => 2400
          s/\x07/␇/g; # and        07 => 2407 … implies that there's
                      # an easy transform that would literally do
                      # \x00 — \0x20 → \u2400 — \u2420 automatically.
                      # damned if I know it though.

__END__

#perl corgifex suggests something like: "\0\1\2"; s/([\x00-\x1f])/"\x{2400}" | $1/eg

that has problems though .. like DEL=127; so he also suggests:

tr(\x00-\x1f)(\x{2400}-\x{241f});  

… which is about as short-and-readable as I think it can get.