[sdiy] keyboard controller MCU protocols (was Re: ...)

[grant musictechnologiesgroup.com]

The Ensoniq thing was the KPC board. In the beforetime, I managed to 
have a handful of these boards and had no need for them. Since they were 
Motorola HC11 boards, and that was my MCU du jour at the time, I used 
them for other odd projects.  I think my projects were small enough to 
fit in the onboard EEPROM, so there was no need to use an external 
EPROM. I did read-out the EPROM for posterity though.

GB

On 8/9/2026 3:49 PM, brianw wrote:
> Anyone interested in protocols similar to MIDI should look for The 'USI', or Universal Synthesizer Interface, by Dave Smith and Chet Wood. It's available for download by AES members from their library. I found it fascinating to see what was proposed before MIDI, and to see the tradeoffs. USI was more flexible in terms of bit depths for all values, but the protocol might take a while to synchronize if you attached the serial cable in the middle of a data stream.
>
> While repairing my Ensoniq Performance Sampler, I learned that their polyphonic aftertouch board has its own processor - which is more powerful that some synthesizers main processor - just for reading the keyboard. Then, between the keyboard processor and the main sampler processor, there is an 8-bit bus ribbon cable, and a protocol something like MIDI. I never bothered to reverse-engineer the protocol (since I was so happy to get the polyAT working again). This board has a name (that I've forgotten) and was used in several keyboards from the EPS to the VFX and maybe beyond.
>
> Adam, are you talking about Roland's DCB? That was supposedly the inspiration for MIDI, but USI came between DCB and MIDI, so it might be quite different.
>
> Brian Willoughby
>
>
> On Aug 8, 2026, at 7:30 PM, Adam wrote:
>> Rainer that's interesting. I wonder if that's similar to the JX3P's communication with the PG-200?
>>
>> A
>>
>> On 9 Aug 2026, at 08:37, Rainer Buchty wrote:
>>> On Sat, 8 Aug 2026, grant musictechnologiesgroup.com wrote:
>>>> I love that the panel MCU is a MIDI controller for the rest. Is this a pretty common technique?
>>> Roland liked to play this game, it seems.
>>>
>>> The JX8P also has a similar setup where the main board and the synth board essentially communicate via MIDI. The differentiation whether it is internal MIDI or "true" MIDI is IIRC a leading 0xf4.
>>>
>>> It's even weirder that one board does MIDI in, and the other does MIDI out ...
>>>
>>> Rainer
>
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