The PCI+ I/O board (Figure B-9) has two PCI bus connectors:
Each connector can accommodate a PCI riser card
Each riser card accommodates one PCI short card
In addition, onboard devices on the PCI+ I/O board provide Fast Ethernet (10/100 Mbit) and Fast/Wide SCSI interfacing.
The board contains five subsystems: I/O (PCI Bus), Memory, Bus Interface, FireHose Interface, and Clock Generation. Four of these subsystems: the I/O (PCI Bus), Memory, Bus Interface and internal board interface subsystems include ASICs. The Clock subsystem distributes and generate clocks for the ASICs and PCI Bus Interfaces on the board