$s = 'AB';
print $s & 0xFC7F;;
Argument "AB" isn't numeric in bitwise and (&) at ...
0

##</code><code>##

$s = unpack 'v', 'AB';;
print pack 'v', $s & 0xFC7F;;
A@

##</code><code>##

$s = 'AB';;
print $s & "\x7F\xFC";;
A@