$/ = \1; # read 1 byte at a time
while(<>) {
    my $ord = ord($_);

    # for each bit in the byte
    for(1 .. 8) {
        if($ord & 1) {
            # do 1 stuff
        }
        else {
            # do 0 stuff
        }

        # move onto the next bit
        $ord >>= 1;
    }
}