Specifications

Figure 7. Layout of the HP 9000 rp7440 and rp8440 Server cell board
Cell design details
Each cell board is a self-contained unit, with an SMP, main memory, and all necessary hardware.
• Processors—Up to four Dual-Core PA-8900 processors (or 8 processor cores/cell board)
• Cell Controller ASIC (CC)
• Memory Mux ASICs
• Main memory DDR-2 DIMMs (up to 16 DIMMs per cell board)
• Voltage regulator modules (VRMs)
• Cell management and processor-dependent hardware (PDH) circuitry
The CC is at the heart of each cell board. It provides the communications link between processors,
memory, I/O, PDH, and adjacent cells. The CC contains interface logic and maintains cache
coherency throughout the system. Adjacent to the cell controller ASIC are up to four PA-8900
processors and up to 256 GB of main memory (currently supports up to 64 GB of main memory using
4-GB DIMMs). Each cell interfaces with adjacent cells and I/O resources directly or, in the case of the
HP 9000 rp8440 Server, to other cells through the crossbar backplane.
The primary function of the Memory Mux ASIC is to multiplex and de-multiplex data between the CC
and the DIMMs in the memory subsystem. When the CC issues a read transaction to the memory
interface command bus, the Memory Mux ASIC buffers the memory read data and returns it as soon
as possible. When the CC issues a write transaction, the memory controller ASIC receives the write
data from the CC and forwards it to the memory.
The sx2000 chipset has twice the memory bandwidth of the sx1000 and over 25% lower memory
access latency when compared to the sx1000.
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