Hi,
i've been exploring OS 1.2 a bit, and i _think_ MIDI channel messages are handled with the routines listed in a jump table 0x5986 - 0x5992. Control change handler is therefore at 0x500e. The handler there loads the received databyte1 into D1 at 0x501e, compares it to recognized controller codes (located in a table at 0x4fd2), and jumps to the corresponding controller handler (based on table at 0x4fe6).
to reverse NRPN and Data Entry MSB/LSB order, maybe it is then enough to just switch the order of the following bytes in the recognized controller codes table ?
0x4fdb : 0x63 0x62 -> 0x4fdb : 0x62 0x63 (for NRPN parameter select) and
0x4fd5 : 0x06 0x26 -> 0x4fd5 : 0x26 0x06 (for data entry)
i haven't tried that though, so chances are that the mod above does not work properly. VS MIDI out NRPN and Data Entry messages seem to be emitted from 0x56fc. At least control codes are there, and D0 input looks like midi channel number.
can you please share where the LFO routine and button codes are located ? thanks :)
jari