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
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Connector Specifications
Connector Standard
DIN 45322 (6-Pin 240° Circular, 1-to-1 straight-through Pin 1->1 .. Pin 6->6 cable)
Bus Driver Logic
5 V Open-Collector (7406 / 74LS06 Hex Inverter + 1 kΩ pull-ups)
Standard Speed
~400 Bytes/sec (VIC-20 / C64 stock); ~4,000 Bytes/sec with JiffyDOS
C128 Burst Mode
Uses Pin 1 (/SRQ IN Fast Serial Clock) with 1571 / 1581 drives!
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| 1 | /SRQ IN (Fast Serial CLK) | I/O | Service Request / C128 & 1571/1581 Fast Serial Burst Clock! (Unused on stock C64/VIC-20) | White / Orange |
| 2 | GND (0 V) | GND | 0 V Common Logic Ground (MUST be connected across all devices!) | Black / Shield |
| 3 | /ATN (Attention) | Out | Active-Low Attention Strobe driven by Computer (CIA2 PA3 / VIA1 PA7) | Brown |
| 4 | /CLK (Serial Clock) | I/O | Active-Low Bidirectional Serial Clock (CIA2 PA4 Out / PA6 In) | Red / Green |
| 5 | /DATA (Serial Data) | I/O | Active-Low Bidirectional Serial Data (CIA2 PA5 Out / PA7 In) | Yellow / Blue |
| 6 | /RESET | Out | Active-Low System Reset (resets 1541/1571 drive when computer is reset) | Purple / Grey |
Troubleshooting DEVICE NOT PRESENT & C128 6-Wire Burst Cables
Created by Bob Yannes and Chuck Peddle for the VIC-20 as a low-cost serial version of the PET's 24-wire IEEE-488 bus, the 6-pin DIN Commodore IEC bus uses three open-collector lines (/ATN, /CLK, /DATA) pulled up to +5 V via 1 kΩ resistors and driven low by 7406 / 74LS06 open-collector inverters. On the Commodore 128 (paired with a 1571 or 1581 drive), Pin 1 (/SRQ IN) is activated as a hardware shift-register Fast Serial Burst clock that speeds up disk transfers by 10x!
- Why Some Cheap 1541 Cables Break C128 Fast Burst Mode: Some cheap aftermarket 1541 cables only wire 5 cores inside the jacket and leave Pin 1 (/SRQ IN) disconnected! For a C128 + 1571/1581, verify continuity on all 6 pins (1-to-1 straight through).
- Diagnosing SEARCHING FOR $ / ?DEVICE NOT PRESENT: With the computer on and no drive plugged in, measure DC voltage on Pins 3, 4, and 5 relative to Pin 2 (GND). All three should sit near +5 V. If any line is stuck at 0 V, the 14-pin 7406 inverter (U8 on C64) has a shorted open-collector output transistor!