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DDR SDRAM Devices
The DDR SDRAM devices used in the RAM expansion modules must be self-refresh type devices for operation
from a 2.5 V power supply. The speed of the DDR SDRAM devices must be 167 MHz or higher.
The devices are programmed to operate with a CAS latency of 2.5 or 3. At these CAS latencies, the access
time from the clock transition must be +/- 0.6 ns or less for data strobes and +/- 0.7 ns for data lines. The
burst length must be at least 4 and the minimum clock delay for back-to-back random column access cycles
must be a latency of 1 clock cycle.
When the computer is in sleep mode, the RAM modules are in self-refresh mode and the maximum
power-supply current available for each RAM module is 6 mA/128 MB (see the section “RAM SO-DIMM
Electrical Limits” (page 56)). Developers should specify DDR SDRAM devices with low power specifications
so as to stay within that limit.
Configuration of DDR RAM SO-DIMMs
Table 4-1 (page 55) shows information about the different sizes of DDR SDRAM devices used in the memory
modules. The first two columns show the memory size and configuration of the SO-DIMMs. The next two
columns show the number and configuration of the DDR SDRAM devices making up the memory modules.
Table 4-1 Sizes of RAM expansion modules and devices
Number of
banks
Device
configuration (MB x
bits)
Number of
devices
SO-DIMM
configuration (MB x
bits)
SO-DIMM size
116 x 8816 x 64128 MB
28 x 16816 x 64128 MB
216 x 81632 x 64256 MB
132 x 8832 x 64256 MB
216 x 16832 x 64256 MB
232 x 81664 x 64512 MB
2x 8128 x 64*1 GB
* 1 GB is a theoretical max and
is reserved for future expansion.
1GB dual die package is not
supported.
RAM Expansion Slots 55
Legacy Document | 2003-03-01 | © 2003 Apple Computer, Inc. All Rights Reserved.
CHAPTER 4
Expansion Features