Editing Ceefax (section)

===Early electro-mechanical system===
{{Unreferenced section|date=December 2014}}
During the late 1960s, engineers Geoff Larkby and Barry Pyatt at the Designs Department (Television Group) of the BBC worked on an experimental analogue text transmission system. Its object was to transmit a printable page of text during the nocturnal "close-down" period of normal television transmission. [[Hugh Greene|Sir Hugh Carleton Greene]], then Director General of the BBC, was interested in making farming and stock-market prices available as hard copy via the dormant TV transmitters. The remit received by BBC Designs Department was "the equivalent of one page of ''The Times'' newspaper to be transmitted during shut-down".

Their system employed a modified rotating-drum facsimile transmitter designed by [[Alexander Muirhead]], and Larkby & Pyatt's own, unique, design of hard-copy printer. This printer used pressure-sensitive "till-roll" paper passing over a drum with a raised helix of steel wire.

The drum was synchronised with the transmission drum by means of the "Start of Page", and "Start of Line" information inherent in the Muirhead system. Printing was effected by a hardened steel blade driven by, initially, a loudspeaker-type moving coil, then by a printed-circuit coil, and finally by a special ceramic piezo element manufactured by [[Clevite|Brush-Clevite]]. The combination of rotating helix and oscillating moving blade, with the till-roll paper moving linearly between them, enabled a raster to be drawn on the paper.