Specifications

CompuLab Ltd. IPC2 – Hardware Specification Page 31 of 83
3.6.4 System Memory Organization Modes
The IMC supports two memory organization modes, single-channel and dual-channel. Depending
upon how the SO-DIMM Modules are populated in each memory channel, a number of different
configurations can exist.
3.6.4.1 Single-Channel Mode
In this mode, all memory cycles are directed to a single-channel. Single-channel mode is used
when either Channel A or Channel B SO-DIMM connectors are populated in any order, but not
both.
3.6.4.2 Dual-Channel Mode (Intel Flex Memory Technology Mode)
The IMC supports Intel Flex Memory Technology Mode. Memory is divided into a symmetric and
asymmetric zone. The symmetric zone starts at the lowest address in each channel and is
contiguous until the asymmetric zone begins or until the top address of the channel with the
smaller capacity is reached. In this mode, the system runs with one zone of dual-channel mode
and one zone of single-channel mode, simultaneously, across the whole memory array.
Note: Channels A and B can be mapped for physical channel 0 and 1 respectively or vice versa;
however, channel A size must be greater or equal to channel B size.
3.6.4.3 Dual-Channel Symmetric Mode
Dual-Channel Symmetric mode, also known as interleaved mode, provides maximum
performance on real world applications. Addresses are ping-ponged between the channels after
each cache line (64-byte boundary). If there are two requests, and the second request is to an
address on the opposite channel from the first, that request can be sent before data from the first
request has returned. If two consecutive cache lines are requested, both may be retrieved
simultaneously, since they are ensured to be on opposite channels. Use Dual-Channel Symmetric
mode when both Channel A and Channel B SO-DIMM connectors are populated in any order, with
the total amount of memory in each channel being the same. When both channels are populated
with the same memory capacity and the boundary between the dual channel zone and the single
channel zone is the top of memory, IMC operates completely in Dual-Channel Symmetric mode.
Note: The DRAM device technology and width may vary from one channel to the other.
3.6.4.4 System Memory Frequency
In all modes, the frequency of system memory is the lowest frequency of all memory modules
placed in the system, as determined through the SPD registers on the memory modules. The
system memory controller supports up to two DIMM connectors per channel. If DIMMs with
different latency are populated across the channels, the BIOS will use the slower of the two
latencies for both channels. For dual-channel mode both channels must have a DIMM connector
populated. For single-channel mode, only a single channel can have a DIMM connector populated.