I cannot help you a lot on this as one would first have to check the sysex implementation thouroughly. Sysex documentation is found on the service manual of the rx7 which is hard to read due to the low contrast of the scans. I did cut down the service manual to the sysex part, raised the contrast and OCR’ed it to be able do text search. I think this may be useful to study the relatively complex sysex implementation. To me, an useful thing would be the editing of voice parameters.
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