Found on the DEC Multia and DEC UDB (Universal Desktop Box). It contains two Serial ports on one connector. The 1st Port is located on the normal pins, and the 2nd port is located on some “spare” pins.
25 PIN D-SUB MALE at the computer
| Pin | Port | Name | Dir | Description |
|---|---|---|---|---|
| 1 | n/c | Not connected | ||
| 2 | 1 | TXD | OUT | Transmit Data |
| 3 | 1 | RXD | IN | Receive Data |
| 4 | 1 | RTS | OUT | Ready To Send |
| 5 | 1 | CTS | IN | Clear To Send |
| 6 | 1 | DSR | IN | Data Set Ready |
| 7 | 1+2 | GND | - | Ground |
| 8 | 1 | DCD | IN | Data Carrier Detect |
| 9 | n/c | Not connected | ||
| 10 | n/c | Not connected | ||
| 11 | 2 | DTR | OUT | Data Terminal Ready |
| 12 | 2 | DCD | IN | Data Carrier Detect |
| 13 | 2 | CTS | IN | Clear To Send |
| 14 | 2 | TXD | OUT | Transmit Data |
| 15 | n/c | Not connected | ||
| 16 | 2 | RXD | IN | Receive Data |
| 17 | n/c | Not connected | ||
| 18 | n/c | Not connected | ||
| 19 | 2 | RTS | OUT | Ready To Send |
| 20 | 1 | DTR | OUT | Data Terminal Ready |
| 21 | n/c | Not connected | ||
| 22 | 1 | RI | IN | Ring Indicator |
| 23 | 2 | DSR | IN | Data Set Ready |
| 24 | n/c | Not connected | ||
| 25 | 2 | RI | IN | Ring Indicator |
Notes
- Direction is DTE (Computer) relative DCE (Modem)