Installation Guide, Fifth Edition - HP 9000 rp7420 Server

Chapter 1
Introduction
Detailed HP 9000 rp7420 Server Description
18
Cell Board
The cell board contains several hardware blocks connected by several data buses. The major hardware blocks
are the Central Processor Units (CPUs), the Cell Controller, the Memory Controllers, and the Memory. Minor
hardware blocks include Clock Distribution, Power Distribution, Reset Circuit, and Platform Dependent
Hardware (PDH) Riser Board Interface. The buses include two Front Side Buses (FBS0 and FBS1), a Memory
(MID) bus, a Crossbar (XB) bus, and an I/O bus. All these blocks come together at the CC chip.
Figure 1-6 Cell Board
The HP 9000 rp7420 Server has a 48-V distributed power system and receives the 48-V power from the
system backplane board. The cell board contains DC-to-DC converters to generate the required voltage rails.
The DC-to-DC converters on the cell board do not provide N+1 redundancy.
Because of space limitations on the cell board, the PDH/PDHC circuitry resides on a riser board that plugs
into the cell board at a right angle. The cell board also includes clock circuits, test circuits, and de-coupling
capacitors.