goutal (12/03/82)
If you really want to see computer-controlled model trains, go to the Tech Model Railroad Club at MIT. (Note that they may not appreciate a deluge of visitors -- I mention this sorta hypothetically...) Last time I was there (circa 1975), (a) the entire setup was controllable via a cast-off crossbar or step-by-step phone exchange; there were various operating stations around the room, each equipped with a controller box and a dial telephone. With the phone you could select a block of track or throw a switch. Once you had "acquired" the train on a particular block, the system would keep track of it for you as it made its way from block to block. The system sensed the position of trains by means of the electrical load on the power supply provided by the engine's motor and by a resistor of something in the caboose -- any caboose or other car so equipped was called an "occupancy car" -- and there was (I think) some inference circuitry to associate a caboose with an engine and all the included blocks. In summary, control was partly automatic, but the system did NOT decide where to route the trains or anything like that. (b) One of their number was working on a yard-controller based on a PDP-11/05, with a special control console to operate it and some fairly intelligent in-yard automatic routing. The idea was that you push buttons on the graphic console (a back- lighted plexiglass affair with pushbuttons embedded in the plexiglass where the various sidings were displayed) to say "Move what's here <*> to over here <*>, and what's on this third siding <*> to this fourth place <*>" and so on, where "<*>" corresponds to pushing a button on the board. The system would then select switching engines to effect the moves, select optimum routes and avoid crashes. Well, that's about the way things stood several years ago. If anyone out there is from TMRC, please do correct/update this info. If you KNOW anyone from TMRC, drag them over to your terminal so they can tell us how things stand today. -- Kenn (decvax!)goutal