my ($from_name, $to_name,
    $from_map,  $to_map);

$from_name = "cp1252.txt";
  $to_name = "cp437.txt";

# Load a codepage file into a Perl data structure
sub load_cp
{
    my ($filename) = @_;
    my (@map);
    open(CP, "<$filename") || die "load_cp: $filename: $!";
    while(<CP>)
    {
        my ($byte, $unicode) = m/^=(..)\tU[+](....)/;
        $map[hex $byte] = hex($unicode);
    }
    return \@map;
}

# Map characters in a file from one codepage to another
sub map_cp
{
    my ($to, $from, $text) = @_;
    my ($new_text, $map, %to, %from, @text);

    # First map codepage "$from" characters to Unicode characters
    foreach my $char (split //, $text)
    {
        if (!defined $from->[ord $char])
        {
            warn "no to=$to_name char for U+$char\n";
        }
        push @text, $from->[ord $char];
    }

    # Now map non-ASCII Unicode characters to codepage "$to"
    foreach my $char (@text)
    {
        if (!defined $to->[$char])
        {
            warn "no from=$from_name char for U+$char\n";
        }
        $new_text .= chr $to->[$char];
    }
    return $new_text;
}

# Load to and from codepages
$from_map = load_cp($from_name);
  $to_map = load_cp(  $to_name);

# Replace \x80 with your text
print map_cp($from_map, $to_map, "\x80");