IBM 440 - Manual (Page 89)

Chapter 3. Planning 75
When a second SMP Expansion Module is installed in the x440, an additional
three SMP Expansion Ports are made available on the rear of the chassis, giving
a total of six. The SMP Expansion Module option includes two cables that are
used to connect the modules together, as shown in Figure 3-5.
Figure 3-5 SMP Expansion Ports with two SMP Expansion Modules installed
Note: The two 10-inch scalability cables used to connect the two SMP Expansion
Modules in a single x440 are included with the SMP Expansion module.
With single-x440 configurations, these ports are used to connect the two internal
SMP Expansion Modules together. Only four ports are used (two cables). The
other two ports are not connected.
When connecting two x440 nodes together to form a 16-way configuration, these
ports are cabled together as shown in Figure 3-6 on page 76.