Samsung ML--6100 - Manual (Page 93)

6. 10 Printer Options
5. Remove the three screws securing the board and pull the board out
of the printer. Unpack the Serial/LocalTalk card or Network card.
Avoid touching its contact pins.
6. Align the connector on the Serial/LocalTalk card or Network card with
the connector on the control board.
Push the card firmly into the connector until it is completely inserted in
place. The two connectors should fit snugly together.
Serial/LocalTalk
card Connector
Network card
Connector
Network Card Serial/LocalTalk Card