The Roland OP-8 interface was designed to control Roland polyphonic synthesizers that were equipped with a DCB (Digital Control Bus) interface via the Roland MC-4 Microcomposer. The OP-8 and synthesizer were connected together usin a DCB cable. The OP-8 and MC-4 Microcomposer were then patched together using patchcords via each of their patchbays. The transpose control on the OP-8 was able to transpose the synthesizer up or down by one octave.
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