Avanti supports up to four PCI slots.  The slots appear as tabs in the Configuration Utility.  The PCI tabs are labeled pci6, pci11, pci12, and pci13, which are the same PCI slot id’s in use on a real AlphaServer 400.  On the real server, pci6 is reserved for the SCSI controller integrated on the main board.  Each PCI slot can be assigned a SCSI controller or a Network card via a drop-down menu at the top of the tab.  Not all PCI slots need to be assigned to build a working virtual Alpha system.

Each Alpha has one dc21071da PCI bus; additional bus blocks are rejected. The four configurable slots are pci6, pci11, pci12 and pci13. Each accepts one NIC or SCSI controller. At most three NICs and at most three SCSI controllers are supported, with no more than four cards in total; DE435 and DE500 cards share the NIC limit. Empty slots are allowed. The ISA serial-card positions isa2, isa3 and isa4 share space with pci13, pci12 and pci11 respectively and cannot be used together with the corresponding PCI slot.

Hand-edited identifiers must use a lowercase pci prefix and a complete unsigned decimal slot number. Leading zeroes retain their decimal meaning: pci6 and pci006 identify the same slot and cannot coexist. Invalid identifiers, duplicate slots, excess cards of either type, and the listed ISA/PCI conflicts prevent configuration loading. The editor refuses a conflicting card selection before removing the previous card. To migrate an older file, preserve its device and backing-file settings while assigning an unused supported slot, or remove an unwanted card. Moving a card can change guest device names, boot selections and network configuration; review those settings before restarting. License-unit charges are unchanged.