Digital Control Bus

[3] DCB functions were basically the same as MIDI, but unlike MIDI (which is capable of transmitting a wide array of information), DCB could provide note on/off, program change and VCF/VCA control only.

DCB-to-MIDI adapters were produced for a number of early Roland products.

The DCB interface was made in 2 variants, the earlier one used 20-pin sockets and cables, later switching to the 14-pin Amphenol DDK connector vaguely resembling a parallel port.

DCB was quickly replaced by MIDI in the early 1980s which Roland helped co-develop with Sequential Circuits.

The latter was capable of saving eight sequences, or a total of 3000 notes, and was capable of transmitting and receiving data via MIDI (though it could not convert signals between DCB and MIDI, nor could it use both protocols simultaneously).

Roland later released the MD-8,[5] a rather large black box capable of converting MIDI signals to DCB and vice versa.

A few other companies offer similar conversion boxes to connect DCB instruments to regular MIDI systems for the support of vintage synthesizers in modern sound production environments; one of the more fully-featured devices being the Kenton PRO-DCB Mk3 which has some bi-directional control limited to a few parameters.

The signals are standard TTL 0-5V, except the Rx Busy output, which is an open collector pulldown.

The DCB is a standard asynchronous serial stream (using an 8251A IC in the JUNO-60), LSB first, 8 data bits, 2 stop bits, odd parity, and a Baud rate of 31.25 kHz.

Identifier is 1 byte using a value F1 through FE, which acts as both a start marker and a message type.

The number of bytes or channels depends on the transmitter's configuration, but doesn't change once communication has been started.