Compaq GS160 - Manual (Page 67)

GS160/320 System Configuration Rules 3-19
The I/O subsystem consists of the local I/O interface (QBB) and the remote I/O
interface (PCI box) connected by I/O cables.
A system can have up to 16 PCI boxes. To identify PCI boxes in a system, a
node ID is set using the node ID switch located on the rear panel of each PCI
box (see Figure 3–11).