Williams tube
In this respect, the Selectron works in the opposite sense of the Williams tube. In the Williams tube, the beam is continually scanning in a read/write cycle which is also used to regenerate data. In contrast, the Selectron is almost always regenerating the entire tube, only breaking this periodically to do actual reads and writes. This not only made operation faster due to the lack of required pauses but also meant the data was much more reliable as it was constantly refreshed.