System 100m modules were built in a unique format, and were all the same size. About 15 modules were offered, consisting mostly of common functions such as VCOs, VCFs, VCAs, and mixers. It was necessary to mount the modules in a case supplied by Roland; the cases, which were offered in 3- and 5-module widths, contained power supplies and an internal bus for internally conveying CV/Gate signals from the keyboard to normalled connections in certain modules (e.g., the pitch CV would be normalled to the frequency input of a VCO). These could be overriden with patch cords. Each module connected to the power supply and the CV/Gate bus via a DIN cable; these protruded from the back of the case and were subject to damage when gigging. The case contained a panel below the module mounting area which