Summary of differences between MMC, SD and other memory cards

Currently on the market more common memory card has SD, MMC, CF, and so on, under the category of these cards are a lot of, the following to summarize.

Refer to Wiki:https://en.wikipedia.org/wiki/memory_card

1,MultiMediaCard (MMC)

In 1997, Siemens and SanDisk introduced multimedia cards that are smaller than CF cards and enable smaller portable devices. In basic applications, MMC can be controlled by a standard three-wire SPI interface plus a chip selection. The SPI interface has a clock frequency of up to 20MHz. For applications that require higher bandwidth, the specification provides a widened 4-and 8-bit bandwidth. The 4.0 version of the MMC specification increases the 52MHZ frequency to support the transfer rate of 50MBPS. Unlike CF, the MMC specification does not exempt from licensing fees. According to the information provided on www.MMCA.org: If you are not an MMC manufacturer, you can order the MMC3.1 or 4.1 (Mmcmobile and Mmcplus) specifications separately for $500 or $1,000, and your company does not need to be a MMCA member.
There are currently several types of memory cards based on the MMC framework, which are: MMC Plus, MMC Mobile, and MMC Micro, EMMC. The Mmcplus is a nominal size MMC card that works at a 2.7~3.6v voltage, has a bus bandwidth of 1, 4, or 8 bits, a minimum of 2.4MBPS read and write performance, and a 26MHz frequency (optionally 52MHz). The mmcmobile is smaller in size and supports lower voltages: 1.65~1.95 V and 2.7~3.6v. The mmcmobile must also support the performance that Mmcplus needs to provide.

Wiki:https://en.wikipedia.org/wiki/multimediacard

2 , Secure Digital   ( SD )

The SD card (Secure Digital memory card) is a new generation of memory devices based on a semiconductor flash memory. The SD card was developed jointly by Panasonic, Toshiba and the American SanDisk Company in August 1999. The SD memory card, which is sized like a postage stamp, weighs only 2 grams, but has high memory capacity, fast data transfer rate, great mobility flexibility and good security. The SD card in the 24mmx32mmx2.1mm volume combines the SanDisk Flash memory card control with MLC (multilevel Cell) technology and Toshiba (Toshiba) 0.16u and 0.13u NAND technology, through the 9-pin interface interface with a dedicated driver, do not need additional power to maintain its memory on the information. And it is an integrated solid medium without any moving parts, so do not worry about mechanical movement damage. Many memory card companies have developed SD card, Panasonic is currently the main SD card manufacturers, 2000 SD card capacity has been from 8MB to 64MB divided into 4 different levels to meet the needs of different occasions, data transmission rate of 2mb/s. By the end of 2001, the single card capacity has been up to 512MB, data transmission rate also increased to 10mb/s. Panasonic plans to launch a high-performance memory card with a capacity of 1GB and a data transfer rate of 20MB/S by 2003, with capacity expected to reach 4GB by 2005.

SD cards are based on several types of SD cards: SDHC, SDXC, SDIO, microSD, etc.

Wiki:https://en.wikipedia.org/wiki/secure_digital#mini-_and_micro-cards

The following types of memory cards are not very common and are listed below for reference:

3. CF Card (Compact Flash)

CF Card (Compact Flash) was first launched by SanDisk in 1994. CF card has Pcmcia-ata function and is compatible with it; CF card weighs only 14g, cardboard match size (43mm x 36m x m3.3mm), is a solid-state product, that is, no moving parts at work. Compact Flash (Flash) technology, CF card is a stable storage solution that does not require a battery to maintain the data stored in it. CF cards are more secure and more protective than traditional disk drives, and are 5 to 10 times times more reliable than traditional disk drives and Ⅲ PC Cards, and the CF card uses only 5% of the size of a small disk drive. The CF card works with voltages between 3.3V and 5V (including 3.3V or 5V). These excellent conditions enable most digital cameras to choose CF cards as their preferred storage medium.
CF card as the world's storage industry standard, to ensure the compatibility of CF products, to ensure the backward compatibility of CF card; with the more and more widely used CF card, the manufacturers actively improve the technology of CF card, promote the new generation of small light, low energy consumption advanced mobile equipment launch, and thus improve work efficiency. CFA headquarters in Palo, Canada
Alto, its members are entitled to free access to CF card, CF trademark and CF technical details. CFA members include 3COM, Canon, Kodak, Hewlett-Packard, Hitachi, IBM, Panasonic, Motorola, NEC, SanDisk, Seiko (Epson) and sockets
Communications and so on more than 120. And one of the major digital camera production research and development companies have set up a specialized organization, engaged in the development of CF products.
CF cards have the following disadvantages:
1, limited capacity. Although the capacity is multiplied, it still cannot catch up with the pixel development of the digital camera. The current 5 million megapixel product is already a popular high-end product minimum specification, while the civilian mainstream market has reached 3 million pixel level. Ordinary civil JPEG compression format, the capacity is fair, but professional-grade TIFF (RAW) format files will not fit a few image data.
2, large size. Compared to other types of memory cards, CF card volume is slightly larger, which also limits the use of CF card Digital camera volume, so popular ultra-thin digital cameras are mostly abandoned CF card, and instead of the smaller size of the SD card.
3, performance limitations. CF card operating temperature is generally 0-40 degrees Celsius. Therefore, in the environment under 0 degrees, digital cameras can be said to become "waste". Even professional machines are not spared. Although the current military CF card cold tolerance to 40 degrees Celsius, but when the popularity, when the price fell to ordinary people can bear the point is still unknown.
At present, the world's largest CF card capacity has reached 640M. The Common Market is 8MB, 16MB, 32MB, 64MB, 128MB, 256MB and so on several (128MB above is Ⅱ type).

4. SM (Smart Media)

The SM (Smart Media) card was a flash memory card released by Toshiba in November 1995, and Samsung purchased production and sales licenses in 1996, and the two companies became the main SM card vendors. In order to promote SmartMedia as an industry standard, the SSFDC forum was established in April 1996 (SSFDC, the solid state floppy Disk Card, actually at the beginning SmartMedia was called SSFDC, Renamed as SmartMedia in June 1996 and became a registered trademark of Toshiba). SSFDC Forum has more than 150 members, also including a number of large manufacturers, such as Sony, Sharp, JVC, Philips, NEC, SanDisk and other manufacturers. SmartMedia cards are also common on the market for micro-storage cards, once in the MP3 player is very popular.
SM Card size is 37mmx45mmx0.76mm, because the SM card itself has no control circuit, and made of plastic (divided into a lot of thin slices), so SM card size is very thin, and was widely used in digital products before 2002, For example, Olympus's old digital cameras and Fuji's old digital cameras use more SM memory card. However, because the SM card control circuit is integrated in digital products (such as digital cameras), which makes the compatibility of digital cameras vulnerable.
At present, the new digital camera has no use of SM memory card products.
5. Memory Stick (Stick)
Sony's always-lone character created the memory stick. This gum-type storage device can be used almost universally on all Sony AV products. Memory Stick
Stick) is lightweight and has a comprehensive range of functions. Its extremely high compatibility and unprecedented "Universal storage media" (Universal
Media) to provide a new generation of higher speed, higher capacity digital information storage and exchange media for future high-tech PCs, televisions, telephones, digital cameras, camcorders and portable personal audio-visual equipment.
In addition to its compact size, high stability and copyright protection, and ease of use in a variety of memory stick products, memory Stick is also the advantage of Sony launched a large number of products using this technology, such as DV camera, digital camera, VAIO pc, color printer, Walkman, IC recorder, LCD TVs, and a full range of accessories such as PC Card converters, 3.5-inch floppy converters, parallel export converters and USB readers make it easy for memory sticks to connect to PCs and Macs.
After the memory stick launch, Samsung, Ai Hua, Sanyo, Casio, Fujitsu, Olympus, Sharp and a series of companies have expressed support for this format. Sony is also looking for a memory stick format for the home electronics industry and IT industry.
In the future, Sony will introduce more products representing the latest development of memory sticks to the domestic market.
One of the shortcomings of memory stick is only used in Sony digital camera, the second is not large enough capacity.
Based on the memory stick, Sony reduced the volume to about 1/3, designed to create a memory Stick Duo, the size of only 31x20x1.6mm, the weight is also reduced by a factor of 2 grams, which is very similar to the XD card, very easy to carry. This memory Stick Duo is handy for use in very small mobile phones and digital cameras, as well as in electronic products such as various MP3 players.
To get greater capacity and speed, Sony introduced a new Memory Stick Pro, developed jointly by Sony and SanDisk, with no change in volume compared to memory sticks, but with 8GB capacity, older devices will not be able to use this new Memory Stick Pro, But now the production of Memory Stick Pro slot digital products can be backwards compatible with the use of traditional memory stick. Memory Stick Pro In addition to serial transmission, but also support parallel transmission, in order to achieve the simultaneous transmission and reception of a variety of data. In parallel transfer mode, the data is transmitted at a speed greater than 160Mbps (theoretical value), making it possible to record a dynamic image of DVD quality in real time. With this high speed, Memory Stick Pro can also support the advanced solutions that come with the upcoming broadband era. Memory Stick Pro has no blue bars and white stripes, and all Memory Stick Pro has a copyright protection feature.
March 2003 Invironment Xu and Hu Whisker ro based on the design and manufacture of Memory Stick Pro
Duo, is an improved product that is a new support for the parallel interface of the past memory Stick Duo. Memory Stick Pro
Duo packs all Memory Stick Pro's advanced features into duo format. It uses higher-density stacking techniques.
Memory Stick Pro
In addition to serial transmission, the duo supports parallel transfer, which transmits data at a speed of 160Mpbs (theoretically maximum). This media responds to the increasing use of high-speed broadband applications, providing a fast, easy way to replicate high-resolution digital images, as well as large-capacity presentation data. Memory sticks allow for the recording of copyrighted content and high-speed data transfer, maintaining high compatibility across a wide range of product areas, including small mobile devices. By connecting the adapter, it can also be applied to products that are compatible with standard size memory sticks.
6, small hard disk (Microdrive)
Microdrive is a large-capacity storage medium introduced by IBM in the United States, the Chinese name is micro hard disk. Due to the lack of large-capacity digital camera storage media, has hindered the development of digital cameras, IBM saw the market gap in this area, combined with its own in the hard disk manufacturing advantages, decisively launched a compact disk with the CF card Ⅱ-type interface, just launched the capacity of up to 340MB, after more than a year of development, The capacity has reached 1G, so that the digital camera in the AVI format to shoot the dynamic image can not be used in seconds to calculate. Of course, the current price to see it is more expensive, but in terms of cost per MB, it is more than the SM card, CF card and Memory stick more cost-effective. In addition, in theory, as long as the support CF card Ⅱ type interface digital camera also support micro-hard disk, but in fact some models such as Epson PC-3000, although the use of Ⅱ-type interface, but does not support micro hard disk. Currently supporting micro-drive digital camera has Casio QV3000EX, Canon PowerShot

7. XD Card
Xd-picture Card (hereinafter referred to as "XD" card) was launched in July 2002. Like Sony's MemoryStick, it's also a proprietary format, so it's hard to find more information from the XD Card official website (www.xd-picture.com). If you want to know how much your company needs to spend to get a license to use the XD card, you must sign a confidentiality agreement with the XD card licensor.

XD has an extremely compact form factor, which is only as large as a postage stamp. The exterior dimensions are only 20x25x1.7mm and weigh only 2 grams. In the memory card domain can be considered to be the smallest. XD card with single-sided 18-pin interface, theoretical storage capacity up to 8gb,2004 years Fuji and Olympus jointly launched a storage capacity of up to 1GB XD card. And its read and write speed is also higher, (read rate is 5mb/s, write rate is 3mb/s around) can satisfy big data volume writes, power consumption is also lower, xd-picture memory card can not only be used for PC adapter card and USB Reader card machine, make it very easy to connect with PC, It also works with the Compact Flash adapter and allows it to be used as a compact Flash card storage medium in a digital camera. Although the current price of XD card is somewhat expensive, but as the flash memory chip and other memory card prices continue to decline, XD card prices will have a greater price reduction space.

xd cards are similar to the SmartMedia standard in that they are packaging technologies for raw NAND flash memory. There is no embedded controller in the XD card, so the control CPU is responsible for maintaining the logic-physical table, managing the bad zone and performing error correction. The advantage of this architecture is that the silicon area is reduced and the management CPU is allowed to have more interface control, thus reducing the write time. The disadvantage of this architecture is that the management CPU must perform all SmartMedia control functions.
The use of XD card precautions
(1) Try not to use the card reader format xd Card, otherwise it may cause the card format error, so that it can not store photos, causing the freezing phenomenon.
(2) When using the card reader transmission image, should use the copy operation, does not carry on the cut operation, but deletes the operation only through the digital camera own deletion function. Otherwise, it can cause memory card failure.

Summary of differences between MMC, SD and other memory cards