Parallel Port based Control

In '93(?), I finally gave in to the impulse and bought a train set at a local hobby store. This was my first attempt at model railroading and computer control of a layout. The layout consisted of a circle with a turnout leading out into an arc parallel to the circle built on our dining table. It used set track. It would be taken apart and stored away when we invited anyone over.

I started off trying to control the layout using the IBM PC parallel printer port. I put together an I/O expander circuit which had one PWM speed control, one point controller and a signal controller driving two lamps. The circuit gave out digital signals which were interfaced to the layout by a block control interface and a turnout control interface.

The software was on DOS and the user interface was very crude. Momentum while starting and stopping the train were provided in software. Unfortunately, after this, I could never ever go back to a throttle without momentum.

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Updated on 14 Nov 95. Feedback to