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MultiMediaCard

From Wikipedia, the free encyclopedia
Not to be confused with SD card.
MultiMediaCard
32 MB MMCplus card
Media typeMemory card
CapacityUp to 512 GB
Developed byJEDEC
Dimensions32 × 24 × 1.4 mm (1.3 × 0.9 × 0.1 in)
Weight2 g (0.071 oz)
UsagePortable devices
Extended toSecure Digital (SD)
Released1997
Computer memory and data storage types
General
Volatile
RAM
Historical
Non-volatile
ROM
NVRAM
Early-stage NVRAM
Analog recording
Optical
In development
Historical

MultiMediaCard, officially abbreviated as MMC, is a memory card standard used for solid-state storage. Unveiled in 1997 by SanDisk, Siemens, and Nokia,[1] MMC is based on a surface-contact low-pin-count serial interface using a single memory stack substrate assembly, and is therefore much smaller than earlier systems based on high-pin-count parallel interfaces using traditional surface-mount assembly such as CompactFlash. Both products were initially introduced using SanDisk NOR-based flash technology.

It has since evolved into several variants, including the widely used SD card and the eMMC (embedded MMC) which is soldered directly onto a device's circuit board. While removable MMC cards have largely been supplanted by SD cards, eMMC remains common in low-cost smartphones, tablets, and budget laptops due to its compact size and affordability, despite being slower and less upgradeable than modern solid-state drives.[2][3][4]

History

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Undersides of an MMC (left) and SD card (right) showing the differences between the two formats

The latest version of the eMMC standard (JESD84-B51) by JEDEC is version 5.1A, released January 2019, with speeds (250 MB/s read, 125 MB/s write) rivaling discrete SATA-based SSDs (500 MB/s).[5]

As of 23 September 2008, the MultimediaCard Association (MMCA) turned over all MMC specifications to the JEDEC organization including embedded MMC (eMMC), SecureMMC, and miCARD assets.[6] JEDEC is an organization devoted to standards for the solid-state industry.

The latest eMMC specifications can be requested from JEDEC, free-of-charge for JEDEC members.[7] Older versions of the standard are freely available, but some optional enhancements to the standard such as MiCard and SecureMMC specifications, must be purchased separately.

While there is no royalty charged for devices to host an MMC or eMMC, a royalty may be necessary in order to manufacture the cards themselves.

A highly detailed datasheet[8] that contains essential information for writing an MMC host driver is available online.

MMC card variants

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Front of four different MMC cards: MMC, RS‑MMC, MMCplus, MMCmobile, and metal extender
Top of four types of MMC cards (clockwise from left): MMC, RS-MMC, MMCplus, MMCmobile, metal extender
Back of four different MMC cards (same cards as above)
Bottom of the same four cards

RS-MMC

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In 2004, the Reduced-Size MultiMediaCard (RS-MMC) was introduced as a smaller form factor of the MMC, with about half the size: 24 mm × 18 mm × 1.4 mm. The RS-MMC uses a simple mechanical adapter to elongate the card so it can be used in any MMC (or SD) slot. RS-MMCs are currently available in sizes up to and including 2 GB.

The modern continuation of an RS-MMC is commonly known as MiniDrive (MD-MMC). A MiniDrive is generally a microSD card adapter in the RS-MMC form factor. This allows a user to take advantage of the wider range of modern MMCs available[9] to exceed the historic 2 GB limitations of older chip technology.

Implementations of RS-MMCs include Nokia and Siemens, who used RS-MMC in their Series 60 Symbian smartphones, the Nokia 770 Internet Tablet, and generations 65 and 75 (Siemens). However, since 2006, all of Nokia's new devices with card slots have used miniSD or microSD cards, with the company dropping support for the MMC standard in its products. While Siemens exited the mobile phone business completely in 2006, the company continues to use MMC for some PLC storage leveraging MD-MMC advances.

DV-MMC

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The Dual-Voltage MultimediaCard (DV-MMC) was one of the first changes in MMC.[citation needed] These cards can operate at 1.8 V in addition to 3.3 V. Running at lower voltages reduces the card's energy consumption, which is important in mobile devices. However, simple dual-voltage parts quickly went out of production in favor of MMCplus and MMCmobile, which offer capabilities in addition to dual-voltage capability.

MMCplus and MMCmobile

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The version 4.x of the MMC standard, introduced in 2005, introduced two significant changes to compete against SD cards: (1) the ability to run at higher speeds (26 MHz and 52 MHz) than the original MMC (20 MHz) or SD (25 MHz, 50 MHz), and (2) a four- or eight-bit-wide data bus.

Version 4.x full-size cards and reduced-size cards can be marketed as MMCplus and MMCmobile, respectively.

Version 4.x cards are fully backward compatible with existing readers but require updated hardware and software to use their new capabilities. Even though the four-bit-wide bus and high-speed modes of operation are deliberately electrically compatible with SD, the initialization protocol is different, so firmware and software updates are required to use these features in an SD reader.

MMCmicro

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MMCmicro

MMCmicro is a smaller version of MMC. With dimensions of 14 mm × 12 mm × 1.1 mm, it is smaller and thinner than RS-MMC. Like MMCmobile, MMCmicro allows dual voltage, is backward compatible with MMC, and can be used in full-size MMC and SD slots with a mechanical adapter. MMCmicro cards have the high-speed and four-bit-bus features of the 4.x spec, but not the eight-bit bus, due to the absence of the extra pins.[10]

This variant was formerly known as S-card when introduced by Samsung on 13 December 2004. It was later adapted and introduced in 2005 by the MultiMediaCard Association (MMCA) as the third form factor memory card in the MultiMediaCard family.[11]

MMCmicro appears very similar to microSD, but the two formats are not physically compatible and have incompatible pinouts.

MiCard

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The MiCard is a backward-compatible extension of the MMC standard with a theoretical maximum size of 2048 GB (2 terabytes) announced on 2 June 2007. The card is composed of two detachable parts, much like a microSD card with an SD adapter. The small memory card fits directly in a USB port and has MMC-compatible electrical contacts. With an included electromechanical adapter, it can also fit in traditional MMC and SD card readers. To date, only one manufacturer (Pretec) has produced cards in this format.[12]

The MiCard was developed by the Industrial Technology Research Institute in Taiwan. At the time of the announcement, twelve Taiwanese companies (including ADATA Technology, Asustek, BenQ, Carry Computer Eng. Co., C-One Technology, DBTel, Power Digital Card Co., and RiCHIP) had signed on to manufacture the new memory card. However, as of June 2011, none of the listed companies had released any such cards, nor had any further announcements been made about plans for the format.

The card was announced to be available starting in the third quarter of 2007. It was expected to save the 12 Taiwanese companies who planned to manufacture the product and related hardware up to US$40 million in licensing fees, which presumably would otherwise be paid to owners of competing flash memory formats. The initial card was to have a capacity of 8 GB, while the standard would allow sizes up to 2048 GB. It was stated to have data transfer speeds of 480 Mbit/s (60 Mbyte/s), with plans to increase data over time.

Embedded MMC

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eMMC chip inside the Samsung Galaxy Tab 2 10.1

The embedded MultiMediaCard (eMMC, officially branded as e•MMC) is a type of internal storage that integrates NAND flash memory,[13] a buffer, and a controller into a single ball grid array (BGA) package. Unlike other forms of removable card-based MMC storage, eMMC is permanently soldered onto a device's printed circuit board (PCB) and is not user-removable or upgradeable. The onboard controller manages tasks such as error correction and data handling, reducing the workload on the device's main processor. eMMC chips use an 8-bit parallel interface and are available in various physical sizes and storage capacities.[14][15]

The eMMC standard was first introduced by the JEDEC Solid State Technology Association in 2006 with version 4.0, which adapted the original card-based MMC specification for embedded (non-removable) and mobile applications.[16] Between 2007 and 2012, the version 4 standard was revised multiple times to improve performance and introduce features such as secure erase and on-system firmware updates. Version 5.0, released in 2013, introduced the HS400 interface mode, enabling theoretical data transfer speeds of up to 400 MB/s, along with enhancements to reliability and boot performance. This was followed by version 5.1 in 2015, which added command queuing and further reliability improvements.[17] The most recent update, version 5.1A, was released in 2019 and included minor refinements to the standard.[18]

eMMC became widely used as the primary storage medium in early smartphones, and later in low-cost laptop computers, Chromebooks, tablet computers, and other compact computing devices. While it was gradually supplanted in higher-performance devices by alternatives such as Universal Flash Storage (UFS) in smartphones and solid-state drives (SSDs) in computers, eMMC continued to be used in entry-level products due to its low cost,[19] compact form factor, low power consumption, and adequate performance for everyday tasks such as web browsing, email, and video streaming.[17]

While eMMC is faster and more power-efficient than traditional hard disk drives, it is slower than most SSDs, especially those using NVMe over PCI Express. These speed limitations make it less suited for applications involving large files or intensive computing needs, such as gaming or video editing. Its lack of upgradeability also limits its appeal in more advanced systems, as users cannot replace or expand storage after purchase.[17]

eMMC versions
Version Sequential read (MB/s) Sequential write (MB/s) Random read (IOPS) Random write (IOPS)
4.5 140[20] 50 7000 2000
5.0 250 90 7,000 13,000
5.1 250 125 11,000 13,000

Similar formats

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In 2004, a group of companies—including Seagate and Hitachi—introduced an interface called CE-ATA for small form factor hard disk drives.[21] This interface was electrically and physically compatible with the MMC specification. However, support for further development of the standard ended in 2008.[22]

The game card format used on the PlayStation Vita was found to be based on the MMC standard, but with a different pinout and support for custom initialization commands as well as copy protection.[23]

See also

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References

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  1. ^ Shendar, Ronni (29 September 2022). "The Invention of the SD Card: When Tiny Storage Met Tech Giants". Western Digital. Retrieved 19 June 2025.
  2. ^ Hunt, Cale (6 February 2023). "eMMC vs. SSD storage: What's the difference?". Windows Central. Archived from the original on 18 February 2024. Retrieved 4 March 2024.
  3. ^ Ree, Brian. "eMMC Memory Modules: A Simple Guide". ODROID Magazine. Archived from the original on 21 September 2023. Retrieved 4 March 2024.
  4. ^ "Orange Pi 32 GB/64GB/256GB eMMC Module". www.orangepi.org. Archived from the original on 6 February 2024. Retrieved 4 March 2024.
  5. ^ "e.MMC v5.1". JEDEC. Retrieved 21 August 2015.
  6. ^ "MultiMediaCard Association Merges with JEDEC | JEDEC". www.jedec.org. Retrieved 29 October 2022.
  7. ^ "Standards & Documents Search | JEDEC". www.jedec.org. Retrieved 29 October 2022.
  8. ^ "MC2GH512NMCA-2SA00 datasheet(1/102 Pages) SAMSUNG | SAMSUNG MultiMediaCard". Html.AllDatasheet.com. 22 September 2005. Retrieved 13 November 2013.
  9. ^ TheMiniDrive.com, http://www.theminidrive.com. Extracted 23 April 2014.
  10. ^ "Samsung Semiconductor Global Official Website" (in Russian). Samsung.com. Retrieved 13 November 2013.
  11. ^ allmemorycards.com, MMCmicro. Extracted 22 April 2006.
  12. ^ "Pretec Announces S-Diamond, 1st in the World to Implement miCARD Standard". Retrieved 21 January 2010.
  13. ^ "NAND and eMMC: All You Need to Know About Flash Memory". 6 September 2016.
  14. ^ "Flash Memory Form Factors". The Fundamentals of Reliable Flash Storage. Hyperstone GmbH. Retrieved 19 April 2018.
  15. ^ "What is eMMC Memory – software support – Reliance Nitro". datalight.com.
  16. ^ "What is eMMC? (embedded MultiMediaCard)". TechTarget. SearchStorage. Retrieved 22 June 2025.
  17. ^ a b c Hunt, Cale (2 October 2024). "eMMC vs. SSD storage: What was the difference, and does it matter now?". Windows Central.
  18. ^ "JEDEC Publishes New UFS, e.MMC, and SPI NOR Flash Standards". JEDEC. 27 February 2019. Retrieved 22 June 2025.
  19. ^ "eMMC Chips".
  20. ^ "eMMC to UFS: How NAND Memory for Mobile Products Is Evolving". news.samsung.com. Retrieved 16 February 2021.
  21. ^ "New Consumer Electronic Interface on Future Hard Drives". Phys.org. Retrieved 1 April 2019.
  22. ^ "Consumer Electronics ATA (CE-ATA)". Technopedia. Retrieved 1 April 2019.
  23. ^ wololo (25 August 2016). "Playstation Vita Cartridge Dump explained". Wololo.net. Retrieved 29 July 2022.
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