pp \$a;;
[Malformed UTF-8 character (fatal) at C:/Perl64/lib/Data/Dump.pm line 458, <STDIN> line 13.

print unpack 'H*', $a;;
Malformed UTF-8 character (byte 0xfe) in unpack at (eval 21) line 1, <STDIN> line 14.
Malformed UTF-8 character (unexpected continuation byte 0x84, with no preceding start byte) in unpack
Malformed UTF-8 character (unexpected continuation byte 0x80, with no preceding start byte) in unpack
Malformed UTF-8 character (unexpected continuation byte 0x80, with no preceding start byte) in unpack
Malformed UTF-8 character (unexpected continuation byte 0x80, with no preceding start byte) in unpack
Malformed UTF-8 character (unexpected continuation byte 0x80, with no preceding start byte) in unpack
Malformed UTF-8 character (unexpected continuation byte 0x80, with no preceding start byte) in unpack
4100000000000000