Toy train sets have existed for almost as long as the originals on which they were modeled, and these were invented for passenger and freight traffic, trade and transport. Commerce and industry were also the driving force behind the development of calculators, electronic brains, i.e. computers. In mock agreement with what has historically turned out to be a rather erroneous idea, that “Computers in the future may weigh no more than 1.5 tons” (Popular Mechanics, March 1949), tons and tons of scaled steel were put together to build this calculating “unicellular creature” on wheels and rails. Ultimately, though the operating system behind such a computing worm is the universal calculator, the Turing machine, which can theoretically calculate whatever is calculable. One would just have to build on and on …

The Turing machine realized here is based on the ideas of Adam Chalcraft and Michael Greene, and manages to read and write using three kinds of points. A sprung point directs trains in one direction and never changes position. A flip-flop point resets itself after a train has passed. A lazy point’s position changes when a train passes over it on its way from the feeder to a specific track. Proceeding from a basic position, the task, the locomotive sets values and states while travelling and then leaves the system—how it has changed is the outcome.

Calculating procedure

In order to set up the track system for input, press the RESET button. This sets all flip-flop points as well as the corresponding lazy points of the six read/write heads in the position “0”. Now the tape is set to “000”, as visible on the illuminated display. The input is written on the display by pressing a combination of the three INPUT buttons, according to the desired calculating procedure. The locomotive travels through the system, sets the read/write heads and reaches the START position. Press the RUN button. The tape is now read by the locomotive and after its journey, the result (output) can be read off the display. The train is able to calculate the following operations:

    Input Output

0+0 000 000 = 0
0+1 010 100 = 1
1+0 100 100 = 1
1+1 101 110 = 2
0+2 011 110 = 2
2+0 110 110 = 2