Apple Performa 6400/180 - Manual (Page 64)

Specifications I/O Interfaces - 10
I/O Interfaces
Apple Desktop Bus
One Apple Desktop Bus (ADB) port supporting up to three ADB
input devices daisy-chained through a synchronous serial bus
PCI Expansion Two PCI expansion slots, compatible with all PCI 2.0
specification-compliant cards with the addition of Macintosh-
OS-specific software driver. Nubus cards cannot be used in
this expansion slot.
Communications
One internal expansion slot for modem or Ethernet card (PCI bus
configuration). Depending on configuration, a modem card may
already be installed.