A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the simulation represents the evolution of the model over time. Often, computers are used to execute the simulation.
Here is a way of faithfully reproducing the movement of a horse: with a rotary switch that enables selection of step, trot, gallop too, gallop to the left and background.
The manner in which the horse puts down its hoofs is indicated clearly by LEDs. The simulator forms, therefore, a versatile demonstration model for instruction and learner riders.
The patterns for driving the LEDs are provided by an EPROM, IC4, whose hex dump in the table shows the relevant addresses and associated data. Addressing is carried out with S3a and counter IC1. Oscillator IC3 ensures that successive addresses are generated automatically. The speed with which the horse moves can be set with P1. The oscillator can also be switched off by closing SI. If that is done, S2 must be pressed briefly before the next pattern is supplied to the LEDs.
When correct addresses are generated, a reset pulse is passed to the counter by 1C3a. The power-up reset is provided by C2 and one of the resistors in array R10• The circuit is operated by a 6 V battery. A separate on-off switch is not required because that function is already provided by Sib. In operation, the circuit draws a current of only 35 mA.
The simulator can be built on a piece of prototyping or a similar board. The only important thing during construction 15 is to ensure that the LEDs are configured as shown, that is, two rows of four LEDs each with D1 at the top left and D5 at the bottom left. The head of the horse is on the right and its tail is on the left.