Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[smilesdavis]

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

• Apple M0197 (1987): System Peripheral-8 Cable • Mini-DIN-8 crossover: 1↔2 • 3↔5 • 6↔8 • 4↔4 • 7↔7 • TG100: M0197

1987	SE / II: GPi pin 7 • modem GPi/RTxC = optional second clock path
1993	660AV / 840AV: GeoPort • modem 9-pin / printer 8-pin • 8-pin compatible • HSKi/Sync/SCLK • GPi/DMA • +5 V pin 9
1996	PowerBook 1400: Mini-DIN-8 • synchronous / asynchronous / AppleTalk • HSKo / HSKi / TxD± / RxD± / GPi
1997	Power Macintosh G3 Beige: printer + modem RS-422 • 230.4 kbit/s internal • 2.048 Mbit/s external clock
1998	PowerBook G3 Wallstreet: 9-pin GeoPort • accepts 8/9-pin • sync/asynch • HSKi ext clock • up to 4 Mbit/s • iMac G3: USB replaces ADB + external serial I/O
1999	Power Macintosh G3 B&W: no RS-422 LocalTalk serial • USB • PowerBook G3 Lombard: USB replaces ADB + serial I/O

Cables / pin topology

• Macintosh RS-422 crossover: 1↔2 • 3↔5 • 6↔8 • 4↔4 • 7↔7
  • Apple System Peripheral-8 M0197 (1987)
  • Yamaha: M0197 pinout
  • LocalTalk / MIDI Time Piece / MIDI Express
  • Roland RSC-15APL

Direct HOST / COMPUTER connections

• Yamaha TG100 (1991): RS-422 • external 1 MHz → Mac HSKi • 8N1 • MTP OFF
• Roland RSC-15APL family: Mac modem/printer • 1 MHz
• Kawai K11: direct Mac modem/printer • 1 MHz
• E-mu SoundEngine: sound module + Mac MIDI interface • internal / MIDI / both • Mac cable • printer/modem thru • interface routing
• Yamaha MU50 (1995): standard Mac cable • Standard MIDI Interface • 1 MHz
• Generalmusic WK4: direct COMPUTER • Mac serial • 1 MHz • Group A / A1–A16 only
• Alesis QS/QSR: MAC 1 MHz • QS pin 1 → Mac pin 2 = 1 MHz bit clock • Mac baud-rate handshake
• Yamaha MU100 (1997): 1 MHz • MTP ON = 32 parts
• Korg NS5R (1997): AG-002B • BPS 31.25 • application clock 1 MHz • KORG MIDI Driver / Apple MIDI Manager

Host-control / virtual-port framing

• Yamaha: TG100 = 1 MHz / MTP OFF → MU50 = F5 Cable Messages • Port 1 internal • Thru 2–8 → MU100 = F5 • Port 1 A1–A16 • Port 2 B1–B16 • Thru 3–8 • 32 parts
• Korg X5DR: 31.25 kbit/s async 8N1 • F5 00/01/02 line control • F5 xx ≠ legal MIDI • driver-inserted control
• Korg NS5R: F5 00 = default Native/Emulate routing • F5 01 = MIDI OUT • F5 02 = Port A • F5 03 = Port B • F5 xx ≠ legal MIDI
• Emagic Unitor8: F5 xx “cable messages” • data format compatible with MOTU MIDI Time Piece • Port 0 = all outputs / MTP Cable 0

Multiport host protocols / MTP compatibility

• Opcode Studio 5: Standard Interface / MTP In/Out views • explicit MTP emulation
• Opcode Studio 4: MTP network interchangeability • MTP presented to OMS as Studio 4 • native protocol more efficient than MTP • non-OMS: MTP emulation / standard-interface mode
• MOTU MIDI Timepiece AV: 8×8 • Mac serial • MTP networking • ≤4 MTPs / 2 per Mac serial port
• MTP AV serial modes: 1 MHz / FAST • FAST ≈2–4× MIDI speed • Macintosh-limited • SysEx caveat
• Emagic Unitor8: 8×8 • MTP emulation • Fast / normal • automatic 1 MHz • OMS / FreeMIDI • AMT
• Midiman BiPort 2x4s: Mac modem/printer serial • 2 In / 4 Out • GeoPort compatible • OMS driver • standard Mac serial cable

Serial replacement / USB transition

• USB ≠ transparent legacy serial replacement: no universal serial↔USB compatibility layer
• GeeThree Stealth / Griffin gPort: Unitor8 ✓ • modem-port compatible • FAST + AMT
• Griffin iPort / Keyspan USB Serial Adapter: Unitor8 ✕ • no external-clock option
• Griffin iPort: other serial MIDI ✓ • tested through Opcode Studio 5
• Keyspan SX Pro: PCI • 4× RS-422 Mini-DIN-8 • ≤1 Mbit/s • MIDI • printer-port emulation
• MegaWolf Romulus / Remus: PCI serial • FreeMIDI • DP 2.5.1 ✓ • Logic 3.7.2 ✓ • Cubase VST 4.0 RX ✕ / TX ✓ • Vision/OMS ✕

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