Service manual

1-50 AlphaServer GS80/160/320 Service Manual
1.13 Clock Generation Modules
AlphaServer GS80/160/320 systems use synchronous data transfers at
high speed. There are three clock domains: the system clock domain,
the I/O clock domain, and the PCI clock domain. There are two clock
generation modules for the system clock: one for systems with one or
two QBBs and one for systems with more than two QBBs. The I/O clock
domain reference is generated on the clock splitter module, and the
PCI clock domain reference is generated on the PCI backplane.
1.13.1 H-switch Clock Module
The H-switch clock module is located in the hierarchical switch
enclosure and distributes the global reference clock signal to the H-
switch and to clock splitters in all QBBs in the system.
Figure 1– 21 H-switch Clock Module