Mac OS 9 Lives

Digital Audio Workstation & MIDI => Audio & MIDI Hardware => Topic started by: smilesdavis on September 01, 2026, 09:06:43 PM

Title: Macintosh Serial MIDI: Hardware, Cables, Clocking, Protocols and Drivers
Post by: smilesdavis on September 01, 2026, 09:06:43 PM

Macintosh Serial MIDI: Hardware, Cables, Clocking, Protocols and Drivers
connector → cable topology → clock → serial framing → port framing → driver/API

Macintosh serial hardware

Year	Macintosh / serial development
1984	128K / 512K: Z8530 SCC • DB-9 • HSKi ext clock • no HSKo / GPi (https://mirrors.apple2.org.za/www.bitsavers.org/pdf/apple/mac/prototypes/1986_Freeport/MacSE_Prototype_Developer_Manual_1986.pdf#page=113)

• Apple M0197 (1987): System Peripheral-8 Cable (https://www.cvxmelody.net/Apple%20Education%20%26%20Government%20Confidential%20Price%20List%20-%20March%202%2C%201987.pdf) • Mini-DIN-8 crossover: 1↔2 • 3↔5 • 6↔8 • 4↔4 • 7↔7 (https://usa.yamaha.com/files/download/other_assets/5/320475/CBXK1XGE.pdf#page=26) • TG100: M0197 (https://chrisarndt.de/files/yamaha/tg100/TG100%20-%20Authorized%20Product%20Manual-%20Complete.pdf#page=87)

1987	SE (https://savagetaylor.com/TIL/TIL12947.pdf#page=3) / II: GPi pin 7 • modem GPi/RTxC = optional second clock path (https://savagetaylor.com/TIL/TIL12932.pdf#page=2)
1993	660AV / 840AV: GeoPort • modem 9-pin / printer 8-pin • 8-pin compatible • HSKi/Sync/SCLK • GPi/DMA • +5 V pin 9 (https://leopard-adc.pepas.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-68K_Desktop/Centris_660AV_Quadra_840AV.pdf#page=51)
1996	PowerBook 1400: Mini-DIN-8 • synchronous / asynchronous / AppleTalk • HSKo / HSKi / TxD± / RxD± / GPi (https://www.macdat.net/files/pdf/apple/developer_notes/powerbook_1400.pdf#page=37)
1997	Power Macintosh G3 Beige: printer + modem RS-422 • 230.4 kbit/s internal • 2.048 Mbit/s external clock (https://savagetaylor.com/TIL/TIL24213.pdf#page=3)
1998	PowerBook G3 Wallstreet: 9-pin GeoPort • accepts 8/9-pin • sync/asynch • HSKi ext clock • up to 4 Mbit/s (https://leopard-adc.pepas.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-G3/PowerBookG3Series.pdf#page=47) • iMac G3: USB replaces ADB + external serial I/O (https://www.wap.org/events/iMacDevNote.pdf#page=19)
1999	Power Macintosh G3 B&W: no RS-422 LocalTalk serial • USB (https://leopard-adc.pepas.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-G3/PowerMacintosh_G3/PowerMacintosh_G3.pdf#page=30) • PowerBook G3 Lombard: USB replaces ADB + serial I/O (https://cdbvs-apple.fr/Manuels%20des%20mac/Power_Book/G3/PowerBook%20G3%20Bronze%20%28Lombard%29.pdf#page=21)

Cables / pin topology

• Macintosh RS-422 crossover: 1↔2 • 3↔5 • 6↔8 • 4↔4 • 7↔7
  • Apple System Peripheral-8 M0197 (1987) (https://www.cvxmelody.net/Apple%20Education%20%26%20Government%20Confidential%20Price%20List%20-%20March%202%2C%201987.pdf)
  • Yamaha: M0197 pinout (https://data.yamaha.com/files/download/other_assets/1/317921/MU5E.pdf#page=22)
  • LocalTalk / MIDI Time Piece / MIDI Express (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=71)
  • Roland RSC-15APL (https://cdn.roland.com/assets/media/pdf/SC-88ST_PRO_OM.pdf#page=76)

Direct HOST / COMPUTER connections

• Yamaha TG100 (1991): RS-422 • external 1 MHz → Mac HSKi • 8N1 • MTP OFF (https://chrisarndt.de/files/yamaha/tg100/TG100%20-%20Authorized%20Product%20Manual-%20Complete.pdf#page=74)
• Roland RSC-15APL family: Mac modem/printer • 1 MHz (https://cdn.roland.com/assets/media/pdf/KR-370_OM.pdf#page=67)
• Kawai K11: direct Mac modem/printer • 1 MHz (https://www.kawai.de/service/k11.pdf#page=18)
• E-mu SoundEngine: sound module + Mac MIDI interface • internal / MIDI / both (https://www.hermannseib.com/documents/SoundEngine.pdf#page=14) • Mac cable • printer/modem thru • interface routing (https://www.hermannseib.com/documents/SoundEngine.pdf#page=26)
• Yamaha MU50 (1995): standard Mac cable • Standard MIDI Interface • 1 MHz (https://www.dosdays.co.uk/media/midi/MU50E1.pdf#page=35)
• Generalmusic WK4: direct COMPUTER • Mac serial • 1 MHz (https://medias.audiofanzine.com/files/wk4-anglais-482063.pdf#page=54) • Group A / A1–A16 only (https://medias.audiofanzine.com/files/wk4-anglais-482063.pdf#page=179)
• Alesis QS/QSR: MAC 1 MHz (https://www.polynominal.com/site/studio/gear/synth/Alesis_qsr/alesis-qsr-manual.pdf#page=23) • QS pin 1 → Mac pin 2 = 1 MHz bit clock • Mac baud-rate handshake (https://www.midiworld.com/quadrasynth/qs_swlib/Alesis-QS-Service-Manual.pdf#page=27)
• Yamaha MU100 (1997): 1 MHz • MTP ON = 32 parts (https://data.yamaha.com/files/download/other_assets/5/333985/MU100E1.pdf#page=34)
• Korg NS5R (1997): AG-002B • BPS 31.25 • application clock 1 MHz (https://cdn.korg.com/us/support/download/files/6d4867399354258f2c4f78803b40ddd1.pdf#page=17) • KORG MIDI Driver / Apple MIDI Manager (https://cdn.korg.com/us/support/download/files/6d4867399354258f2c4f78803b40ddd1.pdf#page=23)

Host-control / virtual-port framing

• Yamaha: TG100 = 1 MHz / MTP OFF (https://chrisarndt.de/files/yamaha/tg100/TG100%20-%20Authorized%20Product%20Manual-%20Complete.pdf#page=74) → MU50 = F5 Cable Messages • Port 1 internal • Thru 2–8 (https://www.dosdays.co.uk/media/midi/MU50E1.pdf#page=115) → MU100 = F5 • Port 1 A1–A16 • Port 2 B1–B16 • Thru 3–8 • 32 parts (https://data.yamaha.com/files/download/other_assets/5/333985/MU100E1.pdf#page=143)
• Korg X5DR: 31.25 kbit/s async 8N1 • F5 00/01/02 line control • F5 xx ≠ legal MIDI • driver-inserted control (https://cdn.korg.com/us/support/download/files/91b3bedfc7b299f60875493c54811a28.pdf#page=184)
• Korg NS5R: F5 00 = default Native/Emulate routing • F5 01 = MIDI OUT • F5 02 = Port A • F5 03 = Port B • F5 xx ≠ legal MIDI (https://cdn.korg.com/us/support/download/files/6d4867399354258f2c4f78803b40ddd1.pdf#page=185)
• Emagic Unitor8: F5 xx “cable messages” • data format compatible with MOTU MIDI Time Piece (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=29) • Port 0 = all outputs / MTP Cable 0 (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=30)

Multiport host protocols / MTP compatibility

• Opcode Studio 5: Standard Interface / MTP In/Out views • explicit MTP emulation (https://audioschematics.dk/wp-content/uploads/media/manuals/midi/studio_5_manual.pdf#page=25)
• Opcode Studio 4: MTP network interchangeability • MTP presented to OMS as Studio 4 • native protocol more efficient than MTP (https://audioschematics.dk/wp-content/uploads/media/manuals/midi/Studio_4_Manual.pdf#page=23) • non-OMS: MTP emulation / standard-interface mode (https://audioschematics.dk/wp-content/uploads/media/manuals/midi/Studio_4_Manual.pdf#page=37)
• MOTU MIDI Timepiece AV: 8×8 • Mac serial • MTP networking • ≤4 MTPs / 2 per Mac serial port (https://www.worldradiohistory.com/Archive-All-Audio/Sound-on-Sound-UK/1997/Sound-on-Sound-1997-01.pdf#page=50)
• MTP AV serial modes: 1 MHz / FAST • FAST ≈2–4× MIDI speed • Macintosh-limited • SysEx caveat (https://cdn-data.motu.com/manuals/midi/MIDI_Timepiece_AV_USB_User_Guide_Mac.pdf#page=16)
• Emagic Unitor8: 8×8 • MTP emulation • Fast / normal • automatic 1 MHz • OMS / FreeMIDI (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=9) • AMT (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=8)
• Midiman BiPort 2x4s: Mac modem/printer serial • 2 In / 4 Out • GeoPort compatible (https://www.manuallib.com/download/pdf15/MIDIMAN-BIPORT-2X4-MANUAL.PDF#page=4) • OMS driver • standard Mac serial cable (https://www.manuallib.com/download/pdf15/MIDIMAN-BIPORT-2X4-MANUAL.PDF#page=25)

Serial replacement / USB transition

• USB ≠ transparent legacy serial replacement: no universal serial↔USB compatibility layer (https://www.wap.org/events/iMacDevNote.pdf#page=31)
• GeeThree Stealth / Griffin gPort: Unitor8 ✓ • modem-port compatible • FAST + AMT (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=18)
• Griffin iPort / Keyspan USB Serial Adapter: Unitor8 ✕ • no external-clock option (https://www.deepsonic.ch/deep/docs_manuals/emagic_unitor8_mkII_amt8_manual.pdf#page=21)
• Griffin iPort: other serial MIDI ✓ • tested through Opcode Studio 5 (https://www.vintageapplemac.com/files/misc/9906.pdf#page=40)
• Keyspan SX Pro: PCI • 4× RS-422 Mini-DIN-8 • ≤1 Mbit/s • MIDI • printer-port emulation (https://www.vintageapplemac.com/files/misc/9904.pdf#page=8)
• MegaWolf Romulus / Remus: PCI serial • FreeMIDI • DP 2.5.1 ✓ • Logic 3.7.2 ✓ • Cubase VST 4.0 RX ✕ / TX ✓ • Vision/OMS ✕ (https://www.vintageapplemac.com/files/misc/9906.pdf#page=40)

Layer distinctions

Mini-DIN-8 shell ≠ cable pinout
HSKi ext clock ≠ GPi/RTxC optional second clock path
1 MHz clock ≠ 1 Mbit/s data
1 MHz ≠ MTP
F5 common byte ≠ common protocol
Yamaha F5 = Cable Message
Korg F5 = line/port control
Emagic F5 = MTP-compatible cable-message format
MTP compatibility ≠ native protocol identity
MTP emulation ≠ native MTP implementation
USB serial ≠ SCC external-clock capability
replacement serial = electrical layer + clocking + port emulation + driver/API

Unresolved byte level

Yamaha F5 ↔ MOTU MTP exact mapping / interoperability
Korg F5 ↔ Yamaha/MTP interoperability
MOTU FAST framing
MTP network RS-422 framing
Opcode native Studio 4/5 framing
Midiman multiport serial framing