UniDIMM (short for Universal DIMM) is a specification for dual in-line memory modules (DIMMs), which are integrated circuits mounted on printed circuit boards (PCBs) and designed to carry dynamic random-access memory (DRAM). UniDIMM modules can be populated with either DDR3 or DDR4 chips, and the computer's memory controller must support both memory standards as UniDIMMs contain no additional memory control logic. The UniDIMM specification was created by Intel for its 2015 Skylake microarchitecture, whose integrated memory controller (IMC) is announced to support both DDR3 and DDR4 memory technologies.[2][3]
UniDIMM is a SO-DIMM form factor with dimensions of 69.6 mm × 30 mm (2.74 by 1.18 inches) for the standard version (which are the same as DDR4 SO-DIMM dimensions[4]), and 69.6 mm × 20 mm (2.74 by 0.79 inches) for the low-profile version.[5][1]:28 UniDIMM has a 260-pin edge connector (the same pin count as for DDR4 SO-DIMMs[4]), with the keying notch in a position that prevents wrong installation by making UniDIMMs physically incompatible with both standard DDR3 and standard DDR4 SO-DIMM sockets. As the DDR4 chips operate at a lower voltage than DDR3 chips (1.2 V versus 1.5 V), UniDIMM modules are designed to contain additional built-in voltage regulation circuitry.[2][1]:27–30
UniDIMM was designed to help the market transition from DDR3 to DDR4 SDRAM. As in previous RAM standard transitions, like from DDR2 to DDR3, there is a "chicken or the egg" problem – as a new product line, the new RAM standard is initially more expensive, yielding low demand and resulting in low production rates. During the DDR2 to DDR3 transition, this was sometimes handled by creating motherboards with separate slots for DDR2 and DDR3 modules, out of which only one set could be used.[6] By its design, UniDIMM specification allows either DDR3 or DDR4 memory to be used in the same memory slots, resulting in no wasted motherboard space that would otherwise be occupied by unused memory slots.[5]
As of September 2014[update], UniDIMM is not standardized by JEDEC,[2] with Kingston and Micron as the main supporters.[1]:28
See also[edit]
- Centaur (computing) – external memory controller for POWER8 chips, providing memory technology independence
- Memory geometry – logical configuration of RAM modules (channels, ranks, banks, etc.)
References[edit]
- ^ a b c d Geof Findley; Becky Loop (September 16, 2014). "DDR4: The Right Memory for Your Next Server and High-End Desktop System" (PDF). intel.activeevents.com. Intel. Retrieved November 28, 2014.
- ^ a b c "How Intel Plans to Transition Between DDR3 and DDR4 for the Mainstream". techpowerup.com. September 14, 2014. Retrieved November 20, 2014.
- ^ Usman Pirzada (September 14, 2014). "Intel Skylake Could Feature Dual DDR3/DDR4 Memory Support with Double IMCs". wccftech.com. Retrieved November 20, 2014.
- ^ a b "DDR4 SDRAM SO-DIMM (MTA18ASF1G72HZ, 8GB) Datasheet" (PDF). Micron Technology. September 10, 2014. pp. 1, 18. Retrieved November 20, 2014.
- ^ a b Usman Pirzada (September 14, 2014). "Intel Launches UniDIMM Initiative – DDR3 and DDR4 RAMs for Laptops and Notebooks". wccftech.com. Retrieved November 20, 2014.
- ^ "Gigabyte DDR2/DDR3 Combo Motherboard: The Upgraders Choice". Gigabyte Technology. 2007. Retrieved November 28, 2014.
External links[edit]
- DDR4 white paper, by Corsair Components
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