The Atari ST, TT, and Falcon030 home computers expose a cartridge expansion port implemented as a 40-pin (20-per-side) edge connector on the left side of the machine. The bus carries a 16-bit data path (D0–D15), a full 16-bit address bus (A1–A15), upper and lower data strobes (UDS/LDS) derived from the Motorola 68000 CPU, and ROM-select lines (RS3, RS4) for gating cartridge ROM banks. Both the host and the cartridge-side connectors share the same 40-pin edge pinout.
| Pin | Name | Description |
|---|---|---|
| 1 | +5V | +5 VDC |
| 2 | +5V | +5 VDC |
| 3 | D14 | Data 14 |
| 4 | D15 | Data 15 |
| 5 | D12 | Data 12 |
| 6 | D13 | Data 13 |
| 7 | D10 | Data 10 |
| 8 | D11 | Data 11 |
| 9 | D8 | Data 8 |
| 10 | D9 | Data 9 |
| 11 | D6 | Data 6 |
| 12 | D7 | Data 7 |
| 13 | D4 | Data 4 |
| 14 | D5 | Data 5 |
| 15 | D2 | Data 2 |
| 16 | D3 | Data 3 |
| 17 | D0 | Data 0 |
| 18 | D1 | Data 1 |
| 19 | A13 | Address 13 |
| 20 | A15 | Address 15 |
| 21 | A8 | Address 8 |
| 22 | A14 | Address 14 |
| 23 | A7 | Address 7 |
| 24 | A9 | Address 9 |
| 25 | A6 | Address 6 |
| 26 | A10 | Address 10 |
| 27 | A5 | Address 5 |
| 28 | A12 | Address 12 |
| 29 | A11 | Address 11 |
| 30 | A4 | Address 4 |
| 31 | RS3 | ROM Select 3 |
| 32 | A3 | Address 3 |
| 33 | RS4 | ROM Select 4 |
| 34 | A2 | Address 2 |
| 35 | UDS | Upper Data Strobe |
| 36 | A1 | Address 1 |
| 37 | LDS | Lower Data Strobe |
| 38 | GND | Ground |
| 39 | GND | Ground |
| 40 | GND | Ground |
References
- Atari ST/STE/TT/Falcon030 Hardware Reference — Atari Corporation (ROM cartridge / expansion port)