Roland's first venture into semi-modular synthesis arrived in 1975 as a modular system you could actually afford and fit in a home studio, which was genuinely revolutionary for the era when synthesizers were still mysterious studio furniture costing tens of thousands of dollars.
The core Model 101 is a compact monophonic synthesizer built around a single voltage-controlled oscillator capable of sawtooth, triangle, square, and pulse width waveforms plus noise generation. It pairs a transistor ladder filter with both low-pass and high-pass modes, an ADSR envelope generator, and an LFO for modulation, all controlled through a 37-note keyboard with plenty of sliders and knobs for real-time sound tweaking. The semi-modular architecture means the signal path is internally hardwired but can be overridden with patch cables, giving you flexibility without the complexity of full modularity. You also get portamento and glide controls, CV and gate outputs, and a handy A-440Hz tuning oscillator.
The genius of the System 100 is its expandability. Pair the 101 with the Model 102 expander, and you've got a second oscillator with ring modulation and sample-and-hold capabilities. The Model 103 mixer brings four channels of stereo mixing with a built-in spring reverb and mono effects send-return, while the Model 104 sequencer offers a two-channel, 12-step pattern sequencer perfect for driving rhythmic sequences. The Model 109 speakers complete the package as a self-contained monitoring solution. Each unit powers independently, so complex patches won't cause pitch drift.
Musicians have consistently praised the System 100 for its warm, beefy character especially in the low end, with that transistor ladder filter delivering squelchy resonance that sits somewhere between clinical and characterful. It became a favorite for early synth-pop and electronic music producers who needed a self-contained creative tool without the learning curve of larger modular systems. The 12-step sequencer format was unconventional for its time but proved ideal for compositional work, and the system's 1V/oct standard means it can interface with modern MIDI-to-CV converters for contemporary setups.
