To clear things up a bit, they are not really used for the programming. The "people friendly" explanation is that each simm has the dip switches set based on it's contents. On iGames, there can be as many as 4 simms that use switches. Each simm will have a different setting based on it's contents, so as the system boots up, it knows that they are there and what it is for. On the s2000, the only simm is the sound simm, and all i960 based games (iGames, s2000's) that use a sound simm expect the sound simm to have all switches in the off position. Anyting other than that, the system will not identify it as sound data.