use warnings;
use strict;

open (my $handle, '<', $ARGV[0]) or 
    die "Unable to open $ARGV[0]: $!";

binmode $handle;
   
while(read ($handle, my $buffer,80)) {

    for my $char (split '', $buffer) {
        my $ord = ord($char); 
        print $ord > 31 && $ord < 128 ? $char : '?'
    }
    print "\n";
}