Roland JX8P, JX10, MKS70 and PG800 Info


The Roland JX8P, JX10 and MKS70 synthesizers use essentially the same 6-note polyphonic voice boards - the 8P having one board and the JX10 and MKS70 having two.

The voice boards feature an 8051 microcontroller which is responsible for the control of the DCOs, software generation of the envelopes and LFO, and control over the analogue filter and VCA sections, as well as the on-board analogue chorus.
The voice boards do not have any storage themselves beyond holding the current tone. They are controlled by the assigner board via an internal serial connection.

The assigner board features a Hitachi 6303 microcontroller, which shares it's memory with a custom Roland keyboard scanning IC which notifies the CPU of any keyboard activity by raising an interrupt.
It is the assigner processor which is responsible for patch and tone storage and editing, the front panel interface, midi reception and (indirectly) transmission, voice allocation and so on.

The assigner processor communicates with the voice boards as follows:

  • The synth's midi input is connected to the serial input on the assigner CPU.
  • The serial output from the assigner CPU is connected to both serial inputs of the voice board CPUs.
  • The serial output from only one of the voice board CPUs is then connected to the synth's midi output.


    • The assigner CPU uses illegal 'midi' commands to tell the voice boards whether it wishes to speak to a specific voice board, whether it wants to address both voice boards at the same time, or if it wants the voice board connected to the midi output to pass the data on to the outside world.
    Once the assigner has established that it is speaking to the voice boards, it uses further non-standard commands to configure the current tone parameters, and also to set the pitch and gate status of each voice.

    The PG800 programmer provides a full set of tone edit controls for the Roland JX8P, JX10 and MKS70 synthesizers.
    The same commands used by the assigner CPU to control the voice boards are also output by the PG800 programmer in response to slider movements, with an extra command to store the tone.
    As the assigner CPU only has one serial interface (in and out), the PG800 is connected to it via a synchronous serial interface.
    In this type of interface, the device that is receiving the data (the synth) is responsible for sending a clock pulse to the transmitting device (the PG) for each data bit it is to receive.
    Once the assigner CPU has received a command from the PG800, it pretty much just passes it straight on to the voice boards. It also stores the changed parameters in the edit buffer in case the user decides to store the edited patch.

    PG800 commands are in a two byte format. The first byte is the command, the second is the data.
    The commands are as follows:

    Command (hex) Voice Param 
    80DCO1 RANG.
    81DCO1 WF .
    82DCO1 TUNE.
    83DCO1 LFO .
    84DCO1 ENV .
    85DCO2 RANG.
    86DCO2 WF .
    87XMOD .
    88DCO2 TUNE.
    89DCO2 FTUN.
    8ADCO2 LFO .
    8BDCO2 ENV .
    8CBEND LFO .
    8FDCO DYNA .
    90DCO MODE .
    91MIX DCO1 .
    92MIX DCO2 .
    93MIX ENV .
    94MIX DYNA .
    95MIX MODE .
    96HPF FREQ .
    97VCF FREQ .
    98VCF RES .
    99VCF LFO .
    9AVCF ENV .
    9BVCF KEY .
    9CVCF DYNA .
    9DVCF MODE .
    9EVCA LEVEL.
    9FVCA DYNA .
    A0CHORUS .
    A1LFO WF .
    A2LFO DELAY.
    A3LFO RATE .
    A4ENV1 ATT .
    A5ENV1 DECY.
    A6ENV1 SUS .
    A7ENV1 REL .
    A8ENV1 KEY .
    A9ENV2 ATT .
    AAENV2 DECY.
    ABENV2 SUS .
    ACENV2 REL .
    ADENV2 KEY .
    AFVCA MODE .

    For futher information on the electrical properties of the interface, refer to the JX8P and PG800, JX10 and MKS70 service manuals, which are still available from Roland.

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    Last update: 3rd March 2001

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