System Memory; Memory Locations And Ordering Rules - IBM S85 pSeries 680 Service Manual

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System Memory

All system memory for the models S80 and S85 system is provided on several sizes of
memory cards, which are plugged into reserved slots.
There are 16 slots available for system memory, and they are located for easy access
from the front or rear of the system rack. These slots are shown in:
"System Rack Locations Front" on page 17
"System Rack Locations Rear" on page 18

"Memory Locations and Ordering Rules"

The memory cards are M01 through M03 and M08 through M10 on the front of the
system, and M11 through M15 and M20 through M24 on the rear of the system.
Memory cards are available in several sizes: 256MB, 512MB, 1024MB, 2048MB, and
4096MB.
Memory Locations and Ordering Rules
The following illustration is a top-level view of the system memory. This view shows a
full configuration of memory cards installed into the system backplane.
R1 memory cards are used in models S80 and S85 systems. All memory cards are
installed in four-card functional units called quads. The quads must be composed of
four cards of the same type. The complete set of four cards must be properly installed
in the proper card slots for the newly installed memory to work correctly. See the
following illustration for the locations of the card slots that are in each quad.
Certain technical applications must have the memory configured for optimal
performance. The memory system of the models S80 and S85 is accessed through two
separate ports. Optimization is achieved by equalizing as much as possible the amount
of memory on each of the ports. Quads A and D are on one port. Quads B and C are
on the other port.
To upgrade the system for optimal performance, sort all of the memory features by
quad size, from largest to smallest. Install the largest memory feature in quad A, insert
the next largest memory feature in quad B. Continue inserting memory quads in the
available quads alphabetically, with the smaller features following the larger.
+5 V dc
Fan monitoring card connector
shows the relative positions to the system rack
shows the relative positions to the system rack
a top view including the processor and clock cards
Chapter 1. Reference Information
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