(#7101) System Unit Expansion 170 only. This feature increases the number of PCI cards and disk units that can be installed in the system. Up to six additional disk units can be supported, with concurrent maintenance. The controller for these disk units resides in the base system. This feature supports up to nine PCI adapter cards (six PCI card slots and three high-speed PCI card slots) driven by two PCI controllers and one Integrated PC server. One PCI controller is included with feature #7101. Maximum: One. Not supported on 2289 processor. The above picture shows 7101 installed on a 170 system unit.