That was something different and much, much simpler. The pay-tv channels would be broadcast unscrabled, unencrypted to the whole cable network. But they would

That was something different and much, much simpler. The pay-tv channels would be broadcast unscrabled, unencrypted to the whole cable network. But they would install notch filters at every subscriber's house to prevent the frequencies of the paid channels from actually entering their house. When you actually paid for HBO, they would send a tech around to your house to remove the corresponding notch filter.