The Quadriga system was developed by the BBC in 1988 using 4 synchronised D1 recorders, 54 MHz sampling, and distributed the signal in such a way that blocks of 4 pixels were sent to each recorder in turn. Thus if a single tape was viewed, the image would appear as a fair but distorted representation of the whole image, enabling edit decisions to be taken on a single recording, and a three-machine edit was possible on a single quadriga by processing each of the four channels in turn, with identical edits made on the other three channels subsequently under the control of a programmed edit controller.