Apple Power Macintosh 4400 - Manual (Page 164)

Note: In order to leave your communication slot available for an Ethernet
card, use an external modem rather than installing an internal modem card.
(An external modem is a separate piece of equipment that sits outside of your
computer and is connected to the external modem port with a cable.) If you
already have an internal modem card in the communication slot and also want
to connect to an Ethernet network, buy and install the kind of Ethernet card
that goes in your computer’s PCI slot. Then follow the instructions in
“Installing a PCI Card” earlier in this section.
Some communication cards designed for other communication slots are not
compatible and cannot be installed here. You can tell by examining the
placement of the notches on the card. Use the following illustration as a guide
if you’re not sure you have the correct type of card.
Compatible
Compatible
Notches Communication card
Notches
Not compatible
Notches
164 Appendix B