Audio Visual Laboratories, a long-defunct but once industry-standard maker of slide projector controls for "multi-media" and multi-image shows and corporate presentations. Their smallest unit, Cricket, could control two Kodak Ektagraphic projectors. Then came Coyote, and Road Runner, which was a control unit only, that needed a Dove dissolve unit for each stack of three projectors. The top of the line was the Eagle II, a CP/M machine, until the Genesis, an IPM PC compatible.
Once programmed, the control signal, Positrack, could be recorded onto a audio track (usually track four) of a reel-to-reel Teac/Tascam 3440 or 34B. Signal was carried by RCA cables, and daisy chained through each Dove.
More at http://en.wikipedia.org/wiki/Eagle_Computer and a tribute page (with some PDF manuals!) at http://www.stevenmichelsen.com/AVL/index.html .