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
Tandy CoCo 4-Pin DIN
Pin 1=/CD In, Pin 2=RS-232 RX In, Pin 3=GND, Pin 4=RS-232 TX Out ( up to 57.6k/115.2k baud!)
BBC Micro 5-Pin Domino
Pin 1=5V/NC, Pin 2=Data Out (TX), Pin 3=GND, Pin 4=Data In (RX), Pin 5=RTS Out, Pin 6/C=CTS In
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| CoCo DIN-4 Pin 1 | /CD (Carrier Detect) | In | CoCo Carrier Detect Input (Connect to PC DE-9 Pin 4 DTR or Pin 7 RTS) | PC DE-9 Pin 4 (DTR) |
| CoCo DIN-4 Pin 2 | RS-232 DATA IN (RX) | In | CoCo Serial Receive Data Input (Connect to PC DE-9 Pin 3 TXD!) | PC DE-9 Pin 3 (TXD) |
| CoCo DIN-4 Pin 3 | GND (0 V Return) | GND | CoCo Serial Signal Ground (Connect to PC DE-9 Pin 5 GND!) | PC DE-9 Pin 5 (GND) |
| CoCo DIN-4 Pin 4 | RS-232 DATA OUT (TX) | Out | CoCo Serial Transmit Data Output (Connect to PC DE-9 Pin 2 RXD!) | PC DE-9 Pin 2 (RXD) |
| BBC Domino Pin 2 | DATA OUT (BBC TX) | Out | BBC Micro RS-423 Transmit Data Out (Connect to PC DE-9 Pin 2 RXD!) | PC DE-9 Pin 2 (RXD) |
| BBC Domino Center 3 | GND (0 V Return) | GND | BBC Micro RS-423 Signal Ground (Center Pin -> PC DE-9 Pin 5 GND!) | PC DE-9 Pin 5 (GND) |
| BBC Domino Pin 4 | DATA IN (BBC RX) | In | BBC Micro RS-423 Receive Data In (Connect to PC DE-9 Pin 3 TXD!) | PC DE-9 Pin 3 (TXD) |
| BBC Domino Pin 5 & 1 | RTS Out (5) & CTS In (1) | I/O | BBC Micro Pin 5 = RTS Out (to PC Pin 8 CTS) | Pin 1 = CTS In (to PC Pin 7 RTS) | Hardware Flow Control |
Running DriveWire 4 on CoCo 1/2/3 & UPURS on BBC Micro
Both the Tandy Color Computer 1/2/3 (4-pin DIN SERIAL I/O) and the Acorn BBC Micro (5-pin Domino DIN RS423) connect directly to a modern PC's 9-pin USB-to-RS232 serial adapter with a simple passive cable — letting you run DriveWire 4 (on CoCo/OS-9) or UPURS / xfer (on BBC Micro) to mount disk images directly from your PC!
- 3-Wire CoCo DriveWire Cable: Wire CoCo 4-pin DIN Pin 2 (RX) -> PC DE-9 Pin 3 (TXD), CoCo Pin 4 (TX) -> PC DE-9 Pin 2 (RXD), and CoCo Pin 3 (GND) -> PC DE-9 Pin 5 (GND). Boot the HDB-DOS ROM (or CoCoSDC) to mount .DSK images over serial at 57,600 baud (CoCo 1/2) or 115,200 baud (CoCo 3)!