Direct Media Interface

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Not to be confused with Desktop Management Interface.

In computing, Direct Media Interface (DMI) is Intel's proprietary link between the northbridge and southbridge on a computer motherboard. It was first used between the 9xx chipsets and the ICH6, released in 2004. Previous Intel chipsets had used the Hub Interface to perform the same function, and server chipsets use a similar interface called Enterprise Southbridge Interface (ESI).[1] While the "DMI" name dates back to ICH6, Intel mandates specific combinations of compatible devices, so the presence of a DMI interface does not guarantee by itself that a particular northbridge–southbridge combination is allowed.

DMI shares many characteristics with PCI Express, using multiple lanes and differential signaling to form a point-to-point link. Most implementations use a ×4 link, while some mobile systems (e.g. 915GMS, 945GMS/GSE/GU and the Atom N450) use a ×2 link, halving the bandwidth. The original implementation provides 10 Gbit/s in each direction using a ×4 link.

DMI 2.0, introduced in 2011, doubles the data transfer rate to 2 GB/s with a ×4 link. It is used to link an Intel CPU with the Intel Platform Controller Hub (PCH), which supersedes the historic implementation of a separate northbridge and southbridge.[2]:14

DMI 3.0, released in August 2015, allows the 8 GT/s transfer rate per lane, for a total of four lanes and 3.93 GB/s for the CPU–PCH link. It is used by two-chip variants of the Intel Skylake microprocessors, which are used in conjunction with Intel 100 Series chipsets;[3][4] some variants of Skylake will have the PCH integrated into the die, effectively following the system on a chip (SoC) design layout.[5] On 9 March 2015, Intel announced the Broadwell-based Xeon D as its first platform to fully incorporate the PCH in an SoC configuration.[6]

Implementations[edit]

Northbridge devices supporting a northbridge DMI are the Intel 915-series, Intel 925-series, Intel 945-series, Intel 955-series, Intel 965-series, Intel 975-series, Intel G31/33, Intel P35, Intel X38, Intel X48, Intel P45, and Intel X58.

Processors supporting a northbridge DMI and, therefore, not using a separate northbridge, are the Intel Atom, Intel Core i3, Intel Core i5, and Intel Core i7 (8xx, 7xx and 6xx, but not 9xx). Processors supporting a northbridge DMI 2.0 and, therefore not using a separate northbridge, are the 2000, 3000, 4000, 5000 and 6000 series of the Intel Core i3, Intel Core i5 and Intel Core i7.

Southbridge devices supporting a southbridge DMI are the ICH6, ICH7, ICH8, ICH9, ICH10, NM10, Intel P55, Intel H55, Intel H57, Intel Q57, Intel PM55, Intel HM55, Intel HM57, Intel QM57, and Intel QS57.

PCH devices supporting DMI 2.0 are the Intel Z68, Intel P67, Intel H67, Intel H61, Intel Q67, Intel Q65, Intel B65, Intel HM65, Intel HM67, Intel QM67, Intel QS67, Intel Z77, Intel Z75, Intel H77, Intel Q77, Intel Q75, Intel B75, Intel X79, Intel HM75, Intel HM76, Intel HM77, Intel UM77, Intel QM77, Intel QS77, Intel Z87, Intel H87, Intel H81, Intel Q87, Intel Q85, Intel B85, Intel Z97, Intel H97, and Intel X99.

Intel Z170 is a PCH device that supports DMI 3.0.

See also[edit]

References[edit]

  1. ^ "Intel 5520 Chipset and Intel 5500 Chipset Datasheet" (PDF). Intel. March 2009. Retrieved 2014-11-06. 
  2. ^ "Desktop 3rd Generation Intel Core Processor Family, Desktop Intel Pentium Processor Family, and Desktop Intel Celeron Processor Family: Datasheet - Volume 1 of 2" (PDF). External Design Specification (EDS). Intel. November 2013. Retrieved 2014-01-28. 
  3. ^ Ian Cutress (2015-08-05). "The Skylake CPU Architecture – The Intel 6th Gen Skylake Review: Core i7-6700K and i5-6600K Tested". AnandTech. Retrieved 2015-08-06. 
  4. ^ Ian Cutress (2015-08-05). "Intel Skylake Z170 Motherboards: A Quick Look at 55+ New Products". AnandTech. Retrieved 2015-08-06. 
  5. ^ Gennadiy Shvets (2014-06-26). "More details on Skylake processors". cpu-world.com. Retrieved 2014-07-01. 
  6. ^ Cutress, Ian (9 March 2015). "Intel Xeon D Launched: 14nm Broadwell SoC for Enterprise". AnandTech. AnandTech. Retrieved 18 June 2015.