The IBM eServer BladeCenter JS20 - IBM Redbooks

2.2.1 Base features
There are two models of the BladeCenter JS20. Both models have the same
base features with the exception of the microprocessors used in the processor
subsystem. The JS20 Type 8842-21X Blade Server uses the PowerPC 970
microprocessor. The JS20 Type 8842-41X Blade Server uses the PowerPC
970FX microprocessor.
Processor subsystem
The processor subsystem of the BladeCenter JS20 is comprised of either two
PowerPC 970 or two PowerPC 970FX microprocessors. They operate at internal
clock frequencies of either 1.6 GHz or 2.2 GHz, respectively.
Each processor includes a 32 KB level 1 data cache, a 64 KB level 1 instruction
cache, and a 512 KB ECC level 2 cache.
Each processor is also interconnected with the rest of the system via a dedicated
interface to the memory controller and host I/O bridge (Northbridge). The
interface to each processor supports a maximum aggregate bandwidth of
6.4 GBps (for processors operating at 1.6 GHz) or 8.8 GBps (for processors
operating at 2.2 GHz).
You can learn more about the features and architecture of the processors in 2.3,
“PowerPC 970 and PowerPC 970FX Microprocessors” on page 29.
Memory subsystem
The memory subsystem is comprised of the memory controller and up to four
DDR1 333 MHz (PC2700) ECC memory modules. The memory controller uses
two-way interleaving to increase the available peak memory bandwidth to 5.3
GBps (333 MHz x 16 bytes).
The BladeCenter JS20 includes two 256 MB memory modules that provide a
total memory capacity of 512 MB. These memory modules are installed in slots 3
and 4. The remaining memory module slots (1 and 2) are empty in the base
BladeCenter JS20.
You can expand the available memory by installing optional memory modules.
The available memory modules are described in “Memory modules” on page 27.
I/O subsystem
The I/O subsystem is connected to the processor and memory subsystems via a
hyper transport link that supports an aggregate bandwidth of 1.6 GBps.
Downstream of this link is a range of I/O devices and expansion interfaces as
explained in the following sections.
24 The IBM Eserver BladeCenter JS20