ThinkaDot.exe provides a working example, if the following explanation is hard to understand. For your virtual machine, you will need some way to reset all the dots to yellow, some way to indicate the initial starting point of a virtual marble (left, middle, or right), and some way to represent the eight dots and change their color from yellow to blue or from blue to yellow. The logic is such that after changing a dot from yellow to blue, the next dot to be reversed is down and to the left. For a blue dot changing to yellow, the next dot to be reversed is down and to the right. A virtual marble dropping down the far left or far right side will only reverse two dots and not three. The folder, ThinkaDot, contains the start of a solution. It provides a picture of the machine, and a flipper control that can be dragged onto the picture just like any other control. The flipper control has a Boolean property, droppedLeft, that tells you the direction the ball fell; and two methods: flip that reverses the control, and reset.

A useful property of Think-a-Dot that can be used for testing, is that a marble dropped into any one of the three holes at the top, eight times in a row, will return the machine to the original pattern. Also, dropping a marble into each of the holes twice will return the machine to the original pattern.