use Term::ReadKey

ReadMode ('cbreak');

print "Press keys to see their ASCII values. Use Ctrl-C to quit.\n"

while (1){
$char = ReadKey (0);
last unless defined $char;
printf("Hex: %x\n", ord($char), ord($char));
}

ReadMode ('normal'); 

##</code><code>##

H Hex: 68
a Hex: 61
l Hex: 6c
l Hex: 6c
o Hex: 6f
  Hex: 20
I Hex: 69
  Hex: 20
a Hex: 61
m Hex: 6d

etc etc etc etc etc