Interactive Connector Diagram
Click or tap any pin in the diagram below to inspect its signal assignment, electrical specification, and wire colour standard.
Click any pin to view its signal assignment, electrical spec, and wire colour.
Used in Retro Machine Hubs
Click any system badge below to jump directly to its dedicated repair, schematic, and diagnostic Machine Hub:
[Amiga Hub — Amiga (A500 / A600 / A1200)]
[Big-Box Amiga Hub — Big-Box Amiga (A1000–A4000)]
[Atari ST Hub — Atari ST (520ST / 1040STF / STE)]
[CPC 6128 Hub — Amstrad CPC 6128]
[CPC 464 Hub — Amstrad CPC 464]
[ZX Spectrum Hub — Sinclair ZX Spectrum (48K / 128K / +3)]
[BBC Micro Hub — BBC Micro (Model B / Master 128)]
[Acorn Hub — Acorn Atom & Electron]
[TRS-80 & CoCo Hub — TRS-80 (Model I/III/4) & CoCo (1/2/3)]
[Osborne/Kaypro Hub — Osborne 1 & Kaypro II CP/M Luggables]
[MSX Hub — MSX (MSX1 / MSX2 / MSX2+ / Turbo R)]
[C128 Hub — Commodore 128 / 128D]
Connector Specifications
All Odd Pins (1–33)
0 V Ground Return (17 ground wires interleaved for crosstalk shielding)
Shugart vs PC DS0
Shugart First Drive = DS0 (Pin 10) | IBM PC Un-Twisted Drive = DS1 (Pin 12)
Pin 34 Difference
Shugart Pin 34 = /READY (Spindle at 300 RPM & Disk In) | PC Pin 34 = /DISK CHANGE
Amstrad 26-Pin 3"
Maps 26-Pin Odd Grounds + Even Signals to 34-Pin (Pin 26->Pin 34 /READY, Pin 12->Pin 10 /DS0)
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| Odd Pins 1–33 | GND (0 V) | GND | All 17 Odd-Numbered Pins (1, 3, 5 .. 33) are 0 V Ground! | All Odd Ribbon Wires |
| 2 | /DSKCHG (Amiga/PC) | /HD | In | Amiga & PC: Active-Low Disk Change! | Shugart 8"/5.25": Head Load | Ribbon Pin 2 |
| 8 | /INDEX | In | Active-Low Index Hole Pulse (1 pulse per revolution = 200 ms @ 300 RPM) | Ribbon Pin 8 |
| 10 | /DS0 (Shugart Drive 0!) | Out | Drive Select 0 (Primary Drive DF0:/A: on Amiga, Atari ST, BBC, CPC, TRS-80!) | Gotek Jumper S0 |
| 12 | /DS1 (Shugart Drive 1 / PC A:) | Out | Drive Select 1 (Secondary Drive on Shugart; Primary on un-twisted PC) | Gotek Jumper S1 |
| 14 | /DS2 | Out | Drive Select 2 | Ribbon Pin 14 |
| 16 | /MOTOR ON | Out | Active-Low Spindle Motor Enable | Ribbon Pin 16 |
| 18 | /DIR (Direction) | Out | Stepper Direction (Low = Step Inward toward Track 79; High = Outward) | Ribbon Pin 18 |
| 20 | /STEP | Out | Active-Low Stepper Pulse | Ribbon Pin 20 |
| 22 | /WDATA (Write Data) | Out | Active-Low FM/MFM Write Data Pulses | Ribbon Pin 22 |
| 24 | /WGATE (Write Gate) | Out | Active-Low Write Enable Gate | Ribbon Pin 24 |
| 26 | /TRK00 (Track 00) | In | Active-Low Track 00 Sensor | Ribbon Pin 26 |
| 28 | /WPT (Write Protect) | In | Active-Low Write Protect Tab Sensor | Ribbon Pin 28 |
| 30 | /RDATA (Read Data) | In | Active-Low Raw FM/MFM Read Data Pulses | Ribbon Pin 30 |
| 32 | /SIDE1 (Head Select) | Out | Side Select (Low = Side 1 Upper Head; High = Side 0 Lower Head) | Ribbon Pin 32 |
| 34 | /READY (Shugart) | /DSKCHG (PC) | In | Shugart/Amiga/CPC/Spectrum +3: /READY! (Required by uPD765A Pin 37!) | Ribbon Pin 34 |
26-Pin Amstrad 3" Drive to 34-Pin Gotek Conversion & 44-Pin 2.5" IDE Power Pins
Nearly every retro computer with a 5.25", 3.5", or 3" floppy drive (Amiga, Atari ST, BBC Micro, Acorn, Amstrad CPC 6128, ZX Spectrum +3, TRS-80, CoCo, MSX, Osborne 1, Kaypro II) uses the 34-pin Shugart SA-400 interface (or its 26-pin compact variant on 3" Hitachi/Matsushita drives). All odd pins (1–33) are Ground (0 V), while all even pins (2–34) carry active-low open-collector signals.
- Amstrad CPC 6128 & ZX Spectrum +3 Internal 26-Pin to 34-Pin Gotek Adapter: On the 26-pin 3" drive ribbon, map 26-pin even pins to 34-pin even pins as follows: 26-Pin 2 -> 34-Pin 8 (/INDEX), 26-Pin 4 -> 34-Pin 10 (/DS0), 26-Pin 8 -> 34-Pin 16 (/MOTOR), 26-Pin 10 -> 34-Pin 18 (/DIR), 26-Pin 12 -> 34-Pin 20 (/STEP), 26-Pin 14 -> 34-Pin 22 (/WDATA), 26-Pin 16 -> 34-Pin 24 (/WGATE), 26-Pin 18 -> 34-Pin 26 (/TRK00), 26-Pin 20 -> 34-Pin 28 (/WPT), 26-Pin 22 -> 34-Pin 30 (/RDATA), 26-Pin 24 -> 34-Pin 32 (/SIDE), and 26-Pin 26 -> 34-Pin 34 (/READY)!
- Amiga A600 / A1200 44-Pin 2.5" IDE Header Warning: Pins 1–40 match standard 40-pin IDE (Pin 1 = /RESET, Pin 20 = Key), while **Pins 41 & 42 carry +5.0 V DC** and **Pins 43 & 44 carry GND**! Never plug an un-keyed 44-pin CF adapter in backwards (Pin 1 Red stripe goes to Pin 1 on the motherboard!), or you will feed +5 V into /RESET and burn the PCB trace!