my $num = "\000\001\002\003\004\005\006\007\010\011\012\013";
my ($bin) = unpack "B*", $num;
print length $bin, ": ", $bin, "\n";
print printable($num), "\n";
$num |= "\000\001\002\003\004\005\006\007\010\377\012\013";
print printable($num), "\n";

sub printable { unpack "H*", $_[0] }