Interactive Connector Diagram
Click or tap any pin in the diagram below to inspect its signal assignment, electrical specification, and wire colour standard.
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:
Connector Specifications
Full Pin Assignment & Wiring Reference
| Pin | Signal Name | Direction | Electrical Spec / Role | Wire Colour / SCART / Adapter Target |
|---|---|---|---|---|
| BBC Tube Pin 17 & 19 | /NTUBE (17) & 2MHz (19) | Out | BBC Micro Tube Chip Select ($FEE0–$FEE7) & 2 MHz Clock (for PiTubeDirect!) | Tube IDC 17 & 19 |
| BBC 1MHz Pin 16 & 18 | /NPGFC (16) & /NPGFD (18) | Out | BBC Micro 1MHz Bus Page FRED ($FC00) & Page JIM ($FD00) Selects | 1MHz IDC 16 & 18 |
| Oric Exp Pin 3 & 5 | /ROMDIS (3) & /MAP (5) | In | Oric Pin 3=/ROMDIS (disables BASIC ROM) | Pin 5=/MAP (enables 16KB Overlay RAM at $C000!) | Erebus / Microdisc |
| Oric Exp Pin 33 & 34 | GND (33) & +5V DC (34) | Pwr | Oric Ground (Pin 33) & +5 V Output (Pin 34 — factory wired on Atmos!) | Power |
| Apple II Slot Pin 1 | /IOSEL ($Cn00–$CnFF) | Out | Apple II Dedicated 256-Byte Slot ROM Select (e.g. $C600 for Slot 6 Disk II!) | Slot Pin 1 |
| Apple II Slot Pin 41 | /DEVSEL ($C080+n*16) | Out | Apple II Dedicated 16-Byte Slot I/O Register Select ($C0E0 for Slot 6) | Slot Pin 41 |
| Apple II Slot 25 & 26 | +5V (25) & GND (26) | Pwr | Apple II Primary +5 V DC (Pin 25) & 0 V Ground (Pin 26; Pin 50=+12V, Pin 33=-12V, Pin 31=-5V) | Power Rails |
Connecting a Raspberry Pi (PiTubeDirect) to the BBC Micro Tube Port
6502 systems provide synchronous expansion buses clocked by Phase 2 (PHI2 / PHI0): the BBC Micro separates high-speed co-processors (40-pin Tube at $FEE0–$FEE7 for 65C02/Z80/ARM/PiTubeDirect) from memory-mapped peripherals (34-pin 1MHz Bus with /NPGFC $FC00 Fred and /NPGFD $FD00 Jim); the Oric-1/Atmos exposes its full 6502A bus on a 34-pin IDC header with /ROMDIS (Pin 3) and /MAP (Pin 5 Overlay RAM enable); and the Apple IIe provides seven 50-pin slots each with its own dedicated 16-byte /DEVSEL ($C080+n*16) and 256-byte /IOSEL ($Cn00–$CnFF) ROM select!
- By plugging a Raspberry Pi Zero (with the passive PiTubeDirect level-shifter board) into the 40-pin Tube IDC header underneath the BBC Micro, you can emulate over 15 Second Processors (3 MHz 65C02, Z80 CP/M, 32016, 68000, and ARM) with zero internal modifications!