| User Port | C+4 Chips' pins | Centronics |
| A | Mass | 16 |
| B | P0 | 2 |
| K | P1 | 3 |
| 4 | P2 | 4 |
| 5 | P3 | 5 |
| 6 | P4 | 6 |
| 7 | P5 | 7 |
| J | P6 | 8 |
| F | P7 | 9 |
| H | DCD | 11 (BUSY) |
| D | RTS | 1 (-STROBE) |
This picture and pieces of code of the driver is taken from book "Alles Uber den PLUS 4".
An example of printing from 1989