{
    local ($\ , $, , $/, $_) = ("\n", "\t", \1034);
    my $somefmt = 'ccc v V '; # add the rest of the format
    open my $in, '<', '/path/to/original.dat' or die $!;
    binmode $in;
    open my $out, '>', '/path/to/outfile.txt' or die $!;
    while (<$in>) {
        my @data = unpack $somefmt, $_;
        # ... adjust @data
        print $out @data;
    }
    close $out or die $!;
    close $in or die $!;
}