Atari 8-Bit Computer
Peripheral (SIO) Port
 |  |
 |  |
| Pin | Description |
|---|---|
| 1 | Clock Input |
| 2 | Clock Output |
| 3 | Data Input |
| 4 | Ground |
| 5 | Data Output |
| 6 | Ground |
| 7 | Command |
| 8 | Motor Control |
| 9 | Proceed |
| 10 | +5V/Ready Disabled on 1200XL. Replace R63 with wire jumper to enable. |
| 11 | Audio Input |
| 12 | +12V on 400 and 800 only. Not connected on XL and XE. |
| 13 | Interrupt |