A semi-modular monophonic synth from Roland , manufactured from 1975 to about 1980, and not to be confused with the System 100m , which appeared later. The System 100 was a somewhat unique concept, as it consisted of a base unit and four optional components. The Model 101 and 102 contain a number of internal normalled connections, which can be overriden by inserting patch cords. There are no normalled connections between the components, so all connections between components must be made using patch cords.