Some network interface cards (NICs) are not supported by most Debian installation disks, such as AX.25 cards and protocols; 3Com EtherLink Plus (3c505) and EtherLink16 (3c507); NI5210 cards; generic NE2100 cards; NI6510 and NI16510 EtherBlaster cards; SEEQ 8005 cards; Schneider & Koch G16 cards; Ansel Communications EISA 3200; Winbond-840 based cards (eg. Realtek-100A), some new Tulip based cards and the Zenith Z-Note built-in network card. These network cards are supported by the "bf2.4" flavor: Winbond-840 based cards, newer Tulip based cards, National Semiconductor DP8381x/DP8382x series and Sundance ST201 "Alta". Microchannel (MCA) network cards are not supported by the standard installation system, but see Linux on MCA for some (old) instructions, and the Linux MCA discussion archives. FDDI networks are also not supported by the installation disks, both cards and protocols. You can create a custom kernel which supports an otherwise unsupported card and then substitute in the installer (see ???).

As for ISDN, the D-channel protocol for the (old) German 1TR6 is not supported; Spellcaster BRI ISDN boards are also not supported by the debian-installer.

Sound devices are not supported by default. But as already mentioned above: if you want to use your own kernel please go to Abschnitt 8.5, „Compiling a New Kernel“ for further information.