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.
Supported Systems / Found On — Retro Machine Hubs
This connector is used on the following retro computer systems. Click any colour-coded badge below to open its full board-level repair, diagnostic, and schematic Machine Hub:
[Atari 2600 / 7800 Hub — Atari 2600 (VCS) & Atari 7800]
[Genesis / Mega Drive Hub — Sega Genesis / Mega Drive]
[Master System Hub — Sega Master System (SMS / Mark III)]
[Sega CD / Mega-CD Hub — Sega CD / Mega-CD (Model 1 & 2)]
[C64 Hub — Commodore 64]
[VIC-20 Hub — Commodore VIC-20]
[C128 Hub — Commodore 128 / 128D]
[SX-64 Hub — Commodore SX-64 Executive]
[Amiga Hub — Amiga (A500 / A600 / A1200)]
[Big-Box Amiga Hub — Big-Box Amiga (A1000–A4000)]
[Atari 8-Bit Hub — Atari 8-Bit (400/800/800XL/130XE)]
[Atari ST Hub — Atari ST (520ST / 1040STF / STE)]
[CPC 464 Hub — Amstrad CPC 464]
[CPC 6128 Hub — Amstrad CPC 6128]
[ZX Spectrum Hub — Sinclair ZX Spectrum (48K / 128K / +3)]
[MSX Hub — MSX (MSX1 / MSX2 / MSX2+ / Turbo R)]
[Wasm Lab — .D64 Parser, 6502 Disassembler & ROM Patcher →]
Connector Specifications
Connector Type
9-Pin D-Sub Male (DE-9M) on console/computer; Female plug on gamepad/joystick
Atari 2600/SMS
Active-Low switches to Pin 8 GND (SMS adds Button 2 on Pin 9; 7800 uses Pins 5 & 9)
Amstrad CPC 464/6128
2-Button Native! Pin 6 = Fire 2, Pin 7 = Fire 1 (NO +5V on Pin 7!), Pin 8 = Joy 0 Common (Row 9), Pin 9 = Joy 1 Common (Row 6 for JY-2 splitter)
Sega Genesis
Pin 5 = +5V VCC, Pin 7 = Select Out (LOW: Up/Down/A/Start; HIGH: Up/Down/Left/Right/B/C)
C64 / Amiga
Pin 7 = +5V VCC; Pins 5 & 9 = C64 SID Paddles or Amiga Middle/Right Mouse Buttons
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| 1 | UP ( / CPC Row 9 Bit 0 / Mouse V ) | In | Digital UP switch (CPC IOA0) | Genesis 6-Btn: Z | Amiga/ST Mouse: V-Pulse | White |
| 2 | DOWN ( / CPC Row 9 Bit 1 / Mouse VQ ) | In | Digital DOWN switch (CPC IOA1) | Genesis 6-Btn: Y | Amiga/ST Mouse: VQ-Pulse | Blue |
| 3 | LEFT ( / CPC Row 9 Bit 2 / Gen X ) | In | Digital LEFT switch (CPC IOA2) | Genesis Select=LOW: Pulled LOW (ID) | 6-Btn: X | Green |
| 4 | RIGHT ( / CPC Row 9 Bit 3 / Mode ) | In | Digital RIGHT switch (CPC IOA3) | Genesis Select=LOW: Pulled LOW (ID) | 6-Btn: Mode | Brown |
| 5 | +5V (Gen/SMS) | POT Y | CPC: NC/F3 | Pwr/In | Sega Genesis & Master System: +5V DC Supply! | C64: Pot Y | Amstrad CPC: NC (or Fire 3) | Yellow |
| 6 | FIRE 1 (Atari/C64) | CPC: FIRE 2 | In | Atari/C64/Amiga: Fire 1 | Amstrad CPC: Fire 2 (IOA4, primary game fire) | Genesis: A/B | Orange |
| 7 | CPC: FIRE 1 | +5V (C64) | Gen: SEL | In/Pwr | Amstrad CPC: Fire 1 (IOA5, 2nd button — NO +5V!) | C64/Atari/Amiga: +5V DC | Genesis: SEL | Red |
| 8 | GND (0 V) | CPC: ROW 9 STROBE (Joy 0) | GND/Out | 0 V Common Switch Return | Amstrad CPC: Keyboard Line 9 Strobe (from 74LS145 Pin 11) | Black (GND / Common) |
| 9 | CPC: ROW 6 (Joy 2) | BTN 2 (SMS) | Out/In | Amstrad CPC: Keyboard Line 6 Strobe (Joy 1 Common via JY-2 splitter!) | SMS: Btn 2 | C64: Pot X | Purple / Grey |
Amstrad CPC 2-Button & Dual-Joystick Splitter Mapping, Genesis 74HC157 & C64 Warning
Introduced on the 1977 Atari VCS (2600), the 9-pin D-Sub male (DE-9M) connector became the universal controller port for both 8/16-bit consoles (Atari 2600, Atari 7800, Sega Master System, Sega Genesis / Mega Drive, Sega CD) and home computers (Commodore, Amiga, Atari 8-Bit/ST, Amstrad CPC, MSX). While Pins 1 (Up), 2 (Down), 3 (Left), 4 (Right), 6 (Fire 1 / Button B), and 8 (Ground) are shared across nearly all systems, Pins 5, 7, and 9 are wired very differently on Sega Genesis (Pin 5 = +5V VCC, Pin 7 = Select Strobe into a 74HC157 multiplexer!), Sega Master System (Pin 9 = Button 2), and Atari 7800 (Pins 5 & 9 = Left/Right Fire via 620 Ω resistors).
- Amstrad CPC 464 / 6128 2-Button & JY-2 Dual-Joystick Splitter Specs: On the Amstrad CPC, the DB9 joystick port is wired directly into the keyboard matrix scanned by the AY-3-8912 (IOA0–IOA5) and 74LS145 BCD decoder. Pin 8 is NOT hardwired to 0V ground — it is Keyboard Row 9 (Joystick 0 strobe)! Closing Up/Down/Left/Right/Fire2(Pin 6)/Fire1(Pin 7) bridges that bit to Pin 8. Because the CPC puts Fire 2 on Pin 6 and Fire 1 on Pin 7 (with NO +5V on Pin 7), standard passive 2-button CPC joysticks work natively, while an Amstrad JY-2 Y-splitter connects a second joystick by wiring Joystick 2's common ground (Pin 8) to CPC DB9 Pin 9 (Keyboard Row 6 strobe)!
- How the Sega Genesis 3-Button & 6-Button Controller Multiplexer Works: Inside every 3-button Genesis pad is a 74HC157 quad 2-to-1 multiplexer powered by +5V on Pin 5. When the Genesis drives Pin 7 (Select) HIGH, Pins 3, 4, 6, 9 report Left, Right, Button B, and Button C. When the Genesis pulls Pin 7 LOW, Pins 3 & 4 are grounded (telling the console a Genesis pad is plugged in) and Pins 6 & 9 report Button A and Start! A 6-button pad counts three rapid Select pulses within 1.5 ms to output X, Y, Z, and Mode on Pins 3, 2, 1, and 4.
- Why Sega Master System & Atari 2600 Joysticks Work Differently: Notice that Sega put +5V on Pin 5 (where Atari/C64 put a Paddle input) and used Pin 7 as the Genesis Select output (where Atari/C64 put +5V, and Amstrad CPC puts Fire 1)! Passive 1-button Atari 2600 joysticks don't connect to Pin 5 or Pin 7, so they can be swapped safely between Atari 2600, SMS, C64, and Amstrad CPC.
- Atari 7800 ProLine 2-Button Wiring: The Atari 7800 keeps full backward compatibility with 1-button Atari 2600 games by wiring both buttons to Pin 6 through diodes, while simultaneously wiring the Left and Right buttons through 620 Ω resistors from Pin 6 to Pin 9 and Pin 5.