Digital Control Bus
Encyclopedia
DCB was a proprietary data interchange interface by Roland Corporation
, developed in 1981 and introduced in 1982 in their Roland Juno-60
and Roland Jupiter-8
products. 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 and program change only. Data was relayed using a thick cable that connected to a port vaguely resembling a parallel port
. DCB-to-MIDI adapters were produced for a number of early Roland products. The DCB interface was made in 2 variants, earlier one used 14-pin sockets and cables, later switching to standard DIN 5-pin plugs
— connectors that became MIDI standard.
and Juno-60
; Roland produced at least two DCB sequencers, the JSQ-60 and the MSQ-700. 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, a rather large black box capable of converting MIDI signals to DCB and vice versa. While this allows note on/off to be sent to a Juno-60 by MIDI, the solution pales in comparison to the full MIDI implementation on the Juno-60's successor, the Roland Juno-106
. A few companies offer similar conversion boxes to connect DCB instruments to regular MIDI systems for support of vintage synths in modern sound production environments.
1. Rx Busy
2. Rx Data
3. Rx Clock
4. Ground
5. Tx Busy
6. Tx Data
7. Tx Clock
The remaining 7 wires may be used for special purposes.
8. Unreg
9. VCA Lower
10. VCA Upper
11. VCF Lower
12. VCF upper
13. VCO-2
14. VCO-1
These are not used in the Juno 60.
7 6 5 4 3 2 1
14 13 12 11 10 9 8
Identifier is 1 byte using a value F1 through FE, which acts as both a start marker and a message type. Data which follows must not use these data bytes. In practice only FD (patch code) and FE (key code) are used.
Data codes are one or more sections or channels, each one byte. The number of bytes or channels depends on the transmitter's configuration, but doesn't change once communication has been started. All data values must be in the range 00-F0.
The end mark is an FF character. It is omitted if the message has a predefined length or the next message starts immediately after the data.
Each channel byte defines a key number (bits 0-6) and whether the key is gated on (1) or off (bit 7).
Keys are identified with 0-96 with zero meaning C0 (16.4Hz), up to 96 C8 (4205Hz).
Channels are assigned in the order defined by the transmitter's key assign mode.
For OP-8, this is Ch1 - Ch8.
For JP-8 split mode, Upper 4 keys followed by Lower 4 keys.
JP-8 dual mode, the data for the first 4 channels is duplicated to the second 4.
If the Juno-60 receives more channels than it physically has voices, the extra channels are "queued" and played later when possible. Whereas the JP-8 only acccepts 8 channels.
Roland Corporation
is a Japanese manufacturer of electronic musical instruments, electronic equipment and software. It was founded by Ikutaro Kakehashi in Osaka on April 18, 1972, with ¥33 million in capital. In 2005 Roland's headquarters relocated to Hamamatsu in Shizuoka Prefecture. Today it has factories in Japan,...
, developed in 1981 and introduced in 1982 in their Roland Juno-60
Roland Juno-60
The Roland Juno-60 is a popular analogue 61-key polyphonic synthesizer produced by Roland Corporation in the early 1980s and a successor to the slightly earlier Juno-6. Like its predecessor, the Juno-60 has some digital enhancements, used only for clocking the oscillators and for saving and loading...
and Roland Jupiter-8
Roland Jupiter-8
The Jupiter-8 is an eight-voice polyphonic analog subtractive synthesizer introduced by Roland Corporation in 1981.The Jupiter-8, or JP-8, was Roland's flagship synthesizer for the first half of the 1980's...
products. 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 and program change only. Data was relayed using a thick cable that connected to a port vaguely resembling a parallel port
IEEE 1284
IEEE 1284 is a standard that defines bi-directional parallel communications between computers and other devices.-History:In the 1970s, Centronics developed the now-familiar printer parallel port that soon became a de facto standard...
. DCB-to-MIDI adapters were produced for a number of early Roland products. The DCB interface was made in 2 variants, earlier one used 14-pin sockets and cables, later switching to standard DIN 5-pin plugs
DIN connector
A DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...
— connectors that became MIDI standard.
Supporting equipment
DCB was quickly replaced by MIDI in the early 1980s. The only DCB-equipped instruments produced were the Roland Jupiter-8Roland Jupiter-8
The Jupiter-8 is an eight-voice polyphonic analog subtractive synthesizer introduced by Roland Corporation in 1981.The Jupiter-8, or JP-8, was Roland's flagship synthesizer for the first half of the 1980's...
and Juno-60
Roland Juno-60
The Roland Juno-60 is a popular analogue 61-key polyphonic synthesizer produced by Roland Corporation in the early 1980s and a successor to the slightly earlier Juno-6. Like its predecessor, the Juno-60 has some digital enhancements, used only for clocking the oscillators and for saving and loading...
; Roland produced at least two DCB sequencers, the JSQ-60 and the MSQ-700. 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, a rather large black box capable of converting MIDI signals to DCB and vice versa. While this allows note on/off to be sent to a Juno-60 by MIDI, the solution pales in comparison to the full MIDI implementation on the Juno-60's successor, the Roland Juno-106
Roland Juno-106
The Roland Juno-106 was a hybrid digital/analogue polyphonic synth manufactured by Roland Corporation in 1984. It featured Digitally controlled oscillators for tuning stability and digital envelope generation along with analog filters and signal path....
. A few companies offer similar conversion boxes to connect DCB instruments to regular MIDI systems for support of vintage synths in modern sound production environments.
Implementation
Following information comes from the Roland Juno 60 Service Notes, First Edition, page 17-19.Physical connection
DCB uses a special 14-wire connection. The first 7 consist of 3 wires in each direction plus a shared ground. The signals are standard TTL 0-5V, except the Rx Busy output, which is an open collector pulldown.1. Rx Busy
2. Rx Data
3. Rx Clock
4. Ground
5. Tx Busy
6. Tx Data
7. Tx Clock
The remaining 7 wires may be used for special purposes.
8. Unreg
9. VCA Lower
10. VCA Upper
11. VCF Lower
12. VCF upper
13. VCO-2
14. VCO-1
These are not used in the Juno 60.
Pinout
View from rear panel. Amphenol DDK connector.7 6 5 4 3 2 1
14 13 12 11 10 9 8
Serial data
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 31.25kHz.Message (Block) Structure)
DCB data is sent in short blocks messages consisting of an identifier, one or more data codes, and an end mark. Blocks may be sent intermittently (JP-8, OP-8) or continuously (Juno 60), in which case end marks are not used.| Identifier/start | Data | Data | ... | End |
|---|---|---|---|---|
| F1-FE | 0-F0 | 0-F0 | ... | FF |
Identifier is 1 byte using a value F1 through FE, which acts as both a start marker and a message type. Data which follows must not use these data bytes. In practice only FD (patch code) and FE (key code) are used.
Data codes are one or more sections or channels, each one byte. The number of bytes or channels depends on the transmitter's configuration, but doesn't change once communication has been started. All data values must be in the range 00-F0.
The end mark is an FF character. It is omitted if the message has a predefined length or the next message starts immediately after the data.
FD: Patch Code Block
This message identifies a patch, by a single byte. Juno 60 ignores this. It is sent once after a patch change, with the first key code by OP-8 and JP-8. It does not have an end mark.FE: Key Code
This message identifies a key event. It contains one byte for each note channel the transmitter supports - so it is 8 bytes long for JP-8 and OP-8, or 6 bytes for Juno 60.Each channel byte defines a key number (bits 0-6) and whether the key is gated on (1) or off (bit 7).
Keys are identified with 0-96 with zero meaning C0 (16.4Hz), up to 96 C8 (4205Hz).
Channels are assigned in the order defined by the transmitter's key assign mode.
For OP-8, this is Ch1 - Ch8.
For JP-8 split mode, Upper 4 keys followed by Lower 4 keys.
JP-8 dual mode, the data for the first 4 channels is duplicated to the second 4.
If the Juno-60 receives more channels than it physically has voices, the extra channels are "queued" and played later when possible. Whereas the JP-8 only acccepts 8 channels.