Anchor machine
From Tardis Wiki, the free Doctor Who reference
Anchor machines — sometimes styled ANCHOR machines — were early, analogue caption generators, unique to the BBC. They were used in the 1960s and 1970s on Doctor Who in scenes which required text or numbers to appear on in-vision computer monitors, such as on the bridge of the Sandminer in The Robots of Death. When used to generate these computer readouts, CSO was required to make the captions slot into the monitor's apparent screen. (DWM 296)