Chapter 4 PA-RISC Computer Systems - OpenPA.net

HP N4000 (rp7405/rp7410) Internals
Chipset
The Cell system architecture has three main components:
1. Cell controller (CC): the central chipset and crossbar. One sits at the centre of each cell board for
a maximum of two in a complete system. The CCs provide links for:
� Four Processors (8.0 GB/s)
� Two Memory “banks” (4.0 GB/s peak)
� I/O via SBA (cell to I/O communication is 2.0 GB/s peak)
� PDH (processor dependent hardware) and firmware/flash etc.
� Second cell via XBC (cell-to-cell communication is 8.0 GB/s peak)
2. Master I/O controller (SBA): the central I/O part of the main chipset. rp7405/rp7410 have two
SBAs, located on the I/O backplane. Each is linked to one cell — with one cell board only one
SBA and its I/O options can be used.
� Each SBA provides sixteen 12-bit links ( “ropes” ) — the combined 32 (2×16) links/ropes
from both SBAs connect to 18 slave I/O controllers (LBAs) which in turn connect the PCI
I/O slots and Core I/O subsystems
� 28 ropes link to 14 “Twin-Turbo” slots (via 14 LBAs)
� Two ropes link to two “Turbo” (that is, normal) PCI slots (via two LBAs), from which one
is reserved for the PCI Core I/O LAN/SCSI card
� Two links/ropes (one from each SBA) are connected via two LBAs to the Core I/O MP/SCSI
card(s)
3. Core I/O card set: provides the standard I/O functions for the system. One of these sets is the
required minimum in any N4000, up to two Core I/O card sets are possible. Each Core I/O
card set contains two distinct cards: MP/SCSI card, installed in a separate slot, and LAN/SCSI,
installed in PCI slot (specially designated, I/O chassis 1, slot 8).
� Two dual-channel Symbios Logic 53C1010 Ultra160 SCSI controllers (on MP/SCSI and
LAN/SCSI)
� Dual-channel Symbios Logic 53C896 Ultra2-Wide SCSI-3 controller (MP/SCSI)
� Gigabit Ethernet networking (LAN/SCSI)
� Diva Serial [GSP] Multiport UART for console (MP/SCSI), serial and management controllers
(MP/SCSI)
� Fast-Ethernet (DEC 21142/43) Management LAN (MP/SCSI)
� The optional second Core I/O card set can be used either for redundancy or partitioning
purpuses (I/O for the second partition)
Other parts of the chipset:
� Prelude SMC memory controllers (on each cell board)
� 18 Elroy PCI bridges (LBAs) convert the links/ropes from the SBA into PCI bus (only 9 of these
18 LBAs are used when only one cell board is installed)
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