MIDI System Exclusive Messages

The KN5000 uses two distinct SysEx formats: Roland GS for incoming voice parameter control, and Technics proprietary for outgoing mode commands. It also implements a bulk data transfer system for panel memory, sound memory, composer data, sequences, and music style programmer (MSP) data.

Outgoing: Technics SysEx

The KN5000 sends short proprietary SysEx messages via MIDI_SendSysExCmd (0xFEBDA3).

Packet Format

F0 50 87 <param> F7
Byte Value Meaning
F0 SysEx start Standard MIDI SysEx header
50 Manufacturer ID Technics/Panasonic (Matsushita)
87 Model ID KN5000 identifier
param Command byte See table below
F7 SysEx end (implicit, appended by MIDI_SendCmdPacket)

Known Command Bytes

Param Context Description
0x08 Sequencer play/stop, drum voice changes, tempo changes, sound mode changes Sound mode reset — signals downstream devices that the KN5000’s sound configuration has changed
0x10 Panel button press (specific modes) Mode change notification — sent when switching between certain operating modes
0x68 Sound initialization Full sound reset — sent during major sound engine reconfiguration

The 0x08 command is by far the most common, with 13 call sites across the firmware. It is sent after any operation that alters the active sound configuration (sequencer start/stop, drum kit selection, tempo changes, accompaniment mode switching).

Implementation

MIDI_SendSysExCmd builds a 4-byte payload on the stack:

ld (xsp + 1), 0xF0    ; SysEx start
ld (xsp + 2), 0x50    ; Manufacturer: Technics
ld (xsp + 3), 0x87    ; Model: KN5000
ld (xsp + 4), a       ; Command byte (from A register)

It then calls MIDI_SendCmdPacket to transmit the packet through the MIDI output port, followed by MIDI_PostSendStub (likely a post-send flush or delay).

Incoming: Roland GS SysEx

The KN5000 receives and processes Roland GS System Exclusive messages for real-time voice parameter control. This is validated by SysEx_ValidateRolandHeader (0xFDAD57).

Expected Header

F0 41 42 12 40 01 <cmd> <data> F7
Byte Value Meaning
F0 SysEx start Standard MIDI SysEx header
41 Manufacturer ID Roland
42 Device ID Fixed device address
12 Command ID DT1 (Data Transfer 1)
40 Model ID GS (General Sound)
01 Sub-category Address high byte
cmd Address mid byte Selects parameter group (see below)
data Parameter value Written to DSP configuration
F7 SysEx end Standard MIDI SysEx terminator

The firmware validates all 6 header bytes sequentially, returning immediately if any mismatch occurs. A maximum of 10 data bytes are accepted (checked via cp c, 0xA at entry).

Command Dispatch

After header validation, the firmware reads the command byte and dispatches to one of four parameter handlers:

Command Handler DSP Config Voice Range Description
0x30 SysEx_ApplyVoiceParam_4B 0x4B00 0-7 (8 voices) Standard voice parameter, bank 4B
0x33 SysEx_ApplyVoiceParam_4B_128 0x4B00 0-127 (128 voices) Extended voice parameter, bank 4B
0x38 SysEx_ApplyVoiceParam_49 0x4900 0-7 (8 voices) Standard voice parameter, bank 49
0x3A SysEx_ApplyVoiceParam_49_128 0x4900 0-127 (128 voices) Extended voice parameter, bank 49

Commands 0x30/0x33 control DSP parameter bank 0x4B (likely mixer/effects), while 0x38/0x3A control bank 0x49 (likely oscillator/filter). The _128 variants allow addressing up to 128 voice slots instead of the standard 8.

Channel Routing

The header’s implicit channel (derived from the SysEx stream position) determines the target voice data base address:

  • Channel 0: Base at 0x00F180 + 0x2E0 — main voice parameter area
  • Channels 1-15: Base at 0x0AB000 + (channel - 1) * 0x800 + 0x2E0 — per-channel voice areas (each channel gets a 2KB block)

Voice Parameter Application

Each handler follows the same pattern:

  1. Clamp the voice index to valid range (0-7 or 0-127) via SysEx_ClampVoiceIndex*
  2. Look up the voice slot from a table (at 0xEE33A4 for 8-voice, 0xEE33AC for 128-voice)
  3. Write the parameter value via DSPCfg_WriteParamSimple
  4. Iterate active voice slots (from DSPCfg_ReadParam_Map0 at 0x4B04/0x4904), applying the same parameter to all matching slots
  5. Restore the original slot ID if the base address was temporarily modified

The per-channel dispatch tables (SysEx_DispatchByChannel at 0xFDAD71, SysEx_DispatchByChannel_49 at 0xFDADA0) route parameters to up to 8 hardware channels, using jump tables at 0xEE3520.

SysEx Parser State Machine

SysEx_ParserLoop (0xFD8D2B) implements a 3-state parser for incoming SysEx streams read from the sequencer buffer:

States (stored at DRAM address 48414)

State Action Transition
0 Wait for 0xF0 (SysEx start) → State 1 on match
1 Check manufacturer ID → State 2 if 0x50, 0x7E, or 0x41; → State 0 otherwise
2+ Accumulate data bytes → Process on 0xF7 (SysEx end); → State 0 on invalid

Accepted Manufacturer IDs

ID Manufacturer Usage
0x41 Roland GS voice parameter commands
0x50 Technics (Panasonic) Proprietary mode commands
0x7E Universal Non-Realtime Standard MIDI extensions (GM System On, etc.)

Data bytes (bit 7 clear) are accumulated via VoiceQueue_Append. The buffer limit is checked against address 48212 (if the 16-bit value at that address reaches 0xFF, further data is rejected). When 0xF7 is received, the accumulated message is processed by SeqData_InitPlaybackFromField.

Bulk Data Transfer (SysEx Exclusive Functions)

The KN5000 supports bulk data transfer for six data types, each with a named handler function (names stored as ROM strings at 0xE555A4-0xE555EC):

Function ROM String Data Type Jump Table Base
ExcSendFunc “ExcSendFunc” Main send dispatch N/A (dispatches to others)
ExcDotFunc “ExcDotFunc” Data Object Transfer 0xE7FD8A
ExcPmemFunc “ExcPmemFunc” Panel Memory (PM1-PM8) 0xE7FDD6
ExcSmemFunc “ExcSmemFunc” Sound Memory banks 0xE7FDEA
ExcCompFunc “ExcCompFunc” Composer/arranger data 0xE7FDFE
ExcSeqFunc “ExcSeqFunc” Sequencer song data 0xE7FE12
ExcMspFunc “ExcMspFunc” Music Style Programmer 0xE7FE26

Handler Architecture

Each Exc*Func handler (except ExcSendFunc) follows an identical pattern:

  1. Subtract 0x1E0003E from the index parameter (XBC) to normalize
  2. Validate range 0-9
  3. Look up a 16-bit handler offset from the type-specific jump table
  4. Dispatch via jp_dri (jump through indexed table)

The handlers support 10 sub-operations (indices 0-9) per data type, covering operations like initiate transfer, send data block, receive data block, verify checksum, and complete transfer.

ExcSendFunc

ExcSendFunc (0xF76688) is the top-level entry point. It validates the message type (0x1C00007), then calls MainExcSend, which dispatches to SysEx_InitiateSend based on an index (0-5) looked up from a table at 0xE7FD84.

SysEx_InitiateSend

SysEx_InitiateSend (0xFD8C7F) configures the SysEx send mode:

  1. Sets bit 7 of the mode byte (DRAM 48380)
  2. Sets the SysEx active flag (bit 6 of DRAM 48408)
  3. Clears all MIDI channel states (MidiChan_ClearAllStates)
  4. Dispatches to one of 6 mode-specific handlers via a jump table at 0xEE2F7E

When the mode is deactivated (bit 7 clear), it clears the SysEx flag and calls SoundMode_ResetAllParams.

Roland GS Compatibility

The KN5000’s acceptance of Roland GS SysEx (manufacturer 0x41) provides compatibility with Roland-format MIDI files and sequencers. This allows:

  • External sequencers using Roland GS protocol to control the KN5000’s voice parameters in real time
  • GS-format MIDI files to play back with correct voice assignments
  • MIDI accompaniment files that embed GS SysEx for voice setup

The command mapping (0x30/0x33 → bank 4B, 0x38/0x3A → bank 49) corresponds to Roland GS address space 40 01 3x, which covers Part parameters in the GS specification:

GS Address Meaning
40 01 30 Tone number (instrument)
40 01 33 Rx. Note On
40 01 38 Scale tuning
40 01 3A CAf Pitch Control

Code References

Symbol Address Purpose
MIDI_SendSysExCmd 0xFEBDA3 Send Technics SysEx (F0 50 87 param)
MIDI_SendCmdPacket 0xFEB55F Low-level MIDI packet transmit
SysEx_ValidateRolandHeader 0xFDAD57 Validate incoming Roland GS header
SysEx_ApplyVoiceParam_4B 0xFDAD9A Apply voice param, bank 4B, 8 voices
SysEx_ApplyVoiceParam_4B_128 0xFDADF2 Apply voice param, bank 4B, 128 voices
SysEx_ApplyVoiceParam_49 0xFDAE58 Apply voice param, bank 49, 8 voices
SysEx_ApplyVoiceParam_49_128 0xFDAEC4 Apply voice param, bank 49, 128 voices
SysEx_DispatchByChannel 0xFDAD71 Route param to channel (bank 4B)
SysEx_DispatchByChannel_49 0xFDADA0 Route param to channel (bank 49)
SysEx_ClampVoiceIndex8 0xFDACD4 Clamp voice index to 0-7
SysEx_ClampVoiceIndex128 0xFDAD07 Clamp voice index to 0-127
SysEx_ParserLoop 0xFD8D2B SysEx stream parser state machine
SysEx_InitiateSend 0xFD8C7F Initiate bulk SysEx send
MidiSysEx_CmdDispatchLoop 0xF24171 MIDI status byte dispatcher (0x81-0xF0)
ExcSendFunc 0xF76688 Main SysEx send handler
ExcDotFunc 0xF766A6 Data Object Transfer handler
ExcPmemFunc 0xF76706 Panel Memory SysEx handler
ExcSmemFunc 0xF76764 Sound Memory SysEx handler
ExcCompFunc 0xF767C2 Composer SysEx handler
ExcSeqFunc 0xF76820 Sequence SysEx handler
ExcMspFunc 0xF7687E MSP SysEx handler

References

Last updated: March 2026