Internal I/O Subsystem - IBM REDPAPER 520Q Technical Overview And Introduction

Figure 2-9 p5-520 or p5-520Q GX+ Bus connection overview
According to the processor speed, the I/O subsystem is capable of supporting 5.6 GBps
when using the 2.1 GHz processor, or capable of supporting 4.4 GBps when using a 1.65
GHz processor. The bus is a dual four-byte wide bus running at a 3:1 processor to bus ratio.

2.5 Internal I/O subsystem

PCI-X, where the
up to 2 GBps, running a 64-bit bus at 133 MHz or 266 MHz. PCI-X is backward compatible,
so the systems can support existing 3.3 volt PCI adapters.
The system planar provides six PCI-X slots and several integrated I/O devices. The PCI-X
slot 1, slot 5, and slot 6 are 64-bit capable running at 133 MHz. The PCI-X slot 2 and slot 3
are 32-bit capable running at 66 MHz, but PCI-X 64-bit short adapters can be used in these
slots.
All the PCI-X slots and the integrated I/O devices, except the PCI-X slot 4, are connected
through two EADS-X chips that function as PCI-X to PCI-X bridges to the Enhanced I/O
Controller. The connections of the PCI-X slots and integrated I/O devices to the PCI-X to
PCI-X bridges are properly distributed to maximize the system performances.
The first three PCI-X slots can accept a short PCI-X or PCI card. The remaining PCI-X slots
are full length cards. PCI-X slot 4 is a PCI-X DDR 266 MHz and 64 bit capable slot and is
driven by the Enhanced I/O Controller directly. The dual 10/100/1000 Mbps Ethernet adapter
and the Dual Channel SCSI Ultra320 adapter are some of the integrated devices on the
system planar.
The PCI-X slots in the p5-520 and p5-520Q system support hot-plug and Extended Error
Handling (EEH). In the unlikely event of a problem, EEH-enabled adapters respond to a
special data packet generated from the affected PCI-X slot hardware by calling system
firmware, which will examine the affected bus, allow the device driver to reset it, and continue
without a system reboot.
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IBM System p5 520 and 520Q Technical Overview and Introduction
Subsystem Subsystem
7311-D20) 7311-D20)
GX+ GX+
Bus Bus
Enhanced Enhanced
DCM DCM
Controller Controller
or or
QCM QCM
Memory Memory
Processor Card Processor Card
X extended
stands for , is an enhanced PCI bus, delivering a bandwidth of
External External
I/O I/O
(up to 4 (up to 4
RIO-2 RIO-2
Card Card
Internal Internal
I/O I/O I/O I/O
Subsystem Subsystem
System Planar System Planar