The back panel of all Power Macintosh models contain two I/O ports for serial telecommunication data. Both sockets accept 9-pin plugs, allowing either port to be independently programmed for asynchronous or synchronous communication formats up to 9600 bps. This includes
AppleTalk and the full range of Apple
GeoPort protocols.
9 pin Apple mini din connector at the end of the peripheral cable, from the front of the connector
| Pin | Signal | Description |
| 1 | SCLK (out) | Reset pod or get pod attention |
| 2 | SCLK (in) | Serial clock from pod (up to 920 Kbit/sec.) |
| 3 | TxD- | Transmit - |
| 4 | GND | Ground |
| 5 | RxD- | Receive - |
| 6 | TxD+ | Transmit + |
| 7 | Wake up / TxHS | Wake up CPU or do DMA handshake |
| 8 | RxD+ | Receive + |
| 9 | +5V | Power to pod (350 mA maximum) |