SD cardMemory card, which is used for mobile phonesDigital camera, laptop, MP3 and othersElectronicsIndependence onstorage medium It is generally the form of card, so it is collectively called "memory card", also known as "digital memory card", "digital memory card", "memory card", etc.
Because the traditional CF card is largeInfineonIn 1997, SanDisk and SanDisk jointly launched a new memory card product, MultiMedia Card (referred to asMMC card）。The size of MMC card is 32mm × 24mm × 1.4mm. It uses a 7-pin interface and has no read-write protection switch.Mainly used in digital cameras, mobile phones (e.gSiemens?MP3、Mobile phone 6688), and somePDAProducts.
RS-MMC
It was launched by MMC Association in 2002, especially for mobile phonesMultimedia productsAnd the designed memory card.RS-MMC is much smaller than MMC, and it can be used with specialAdapterConvert to standard MMC card for use.
MMC PLUS
In September 2004, MMC Association launched MMC PLUS and MMC moboile.MMC PLUS card is the same size as ordinary MMC card and has faster reading speed.Some factories and businesses have also launched low-voltage MMC PLUS.
MMC moboile
In order to obtain better power saving performance, MMC Association has introduced a memory card that can not only work at low voltage but also be compatible with the original RS-MMC - MMC mobile. It can work at 1.65~1.95V and 2.7~3.6V, with a theoretical transmission speed of up to 52MB/s.It is called dual voltage RS-MMC.The size of the MMC mobole is exactly the same as that of the RS-MMC card. The biggest difference is that the MMC mobole has 13Goldfinger。
MMC micro
comparisonmicroSD card and MMC micro are slightly larger, 12mm × 14mm × 1.1mm.Like MMC mobole, it supports dual voltage, which is suitable for size andBattery enduranceHigh demand mobile phones and other handheld devicesPortable equipment。
Secure Digital card is called SD card for short. Literally, this card is a security card, which is more than CF card and earlierSM cardMore excellent in safety performance.PanasonicToshibaAnd SanDiskCo developmentAs a new memory card product, the biggest feature is to ensure the security and confidentiality of data through the encryption function.SD card can be seen as an upgrade of MMC in many aspects.Both of them have the same shape and working mode, but the MMC card is slightly thinnerSD cardAll machines of the device can use MMC cards.hisOverall dimension32mm × 24mm × 2.1mm.
miniSD
The SD card is a little bulky for small digital products such as mobile phones. At the same time, in order to catch up with Duo and Xd, the SD card camp released a smaller memory card, called“miniSD”。Its overall dimension is 20mm × 21.5mm × 1.4mm, its package area is 44% of the original SD card, its volume is 63% of the original SD card, and it has 11 golden fingers (only 9 SD cards).adoptThe adapter cardIt can also be used as an SD card.The card is inDopod、PanasonicIt is widely used on mobile phones.
microSD
The microSD card standard was referenced by the SD Association in 2005-FlashOfRelevant standardsDeveloped, T-Flash card and microSD cardThey are compatible with each other.AndMiniSD cardCompared with the standard SD card, the microSD card has a smaller size of 11mm × 15mm × 1.4mm. It is only about a quarter of the standard SD card and is the smallest memory card in the market at present.
Full name:TransFLash, byMotorolaIt was jointly developed with SANDISK and launched in 2004.It is a subminiature card (11 * 15 * 1MM), about 1/4 of the SD card, which is the smallest storage card at present.TF cardIt can be used as SD card after SD card converter.The adapter can be used on the device using SD as the storage medium.TransFlash is mainly used forcamera phone It is developed for shooting large images and downloading large video clips.TransFlash cardIt can be used to store personal data, such as digital photos, MP3, games, and applications and personal data for mobile phonescopyright protection Management system, letDownloaded music, videos and games are protected;The new TransFlash introduced in the future is also equipped with encryption function to protect personal data, financial records and health care documents.The compact TransFlash allows manufacturers to adopt this design without worrying about the size of the phone, while another flexible application is to enablesupplierIt can be replaced at any time according to different needs of customers before delivery, which has the advantage of[1]Embedded flash memory does not.
◆ It can be used on digital products with SD card slot after matching with adapter.
◆ Size: 11mm * 15mm * 1mm.
SDHC
SDHCIs the abbreviation of "Secure Digital High Capacity", that is“High capacitySD memory card”。In May 2006, the SD Association released the latest version of the SD 2.0 system specification, which stipulates that SDHC conforms to the new specification and has a capacity greater than 2GBLess than or equal to32GBSD card
The biggest feature of SDHC is its high capacity (2GB-32GB).In addition, the SD Association stipulates that SDHC must adoptFAT32File system, which is used in SD card beforeFAT16The maximum capacity supported by the file system is 2GB, which cannot meet the requirements of SDHC.
As the successor of SD Card, SDHC is mainly characterized byfile formatFrom previousFAT12FAT16 has been upgraded to FAT32, and the maximum support is 32GB.At the same time, the transmission speed is redefined asClass2(2MB/sec), Class4 (4MB/sec), Class6 (6MB/sec), etc. High speed SD cards can support high resolutionvideo recording Real time storage of.
The overall dimension of SDHC card is 32 × 24 × 2.1mm (length × width × height), which is the same as that of SD card,copyright protectionThe functions are also the same as before, but because the file system has been changed, the SD devices that previously only supported FAT12/16 format are incompatible, and also support FAT32 (SDHC) machines, which can read the existing SD cards in FAT12/16 format.
All SD cards with a capacity greater than 2G must comply with the SDHC specification, which indicates that the SDHC must at least comply with the speed class of Class 2, and the card must have the SDHC mark and the speed class mark.
In the market, there are some brands that provide 4GB or higher capacity SD cards that do not meet the above conditions, such as the lack of SDHC logo or speed level logo. These memory cards cannot be called SDHC cards. Strictly speaking, they are not recognized by the SD Association. Such cards are likely to have compatibility problems with equipment in use.
SDXC
SD AssociationCES2009 shows a 2TB[3]SDXCMemory card (SD eXtended Capacity).
SDXC not only has huge capacity, but alsoData transmission speedIt is also good. It is reported that its maximum transmission speed is expected to reach 300MB/s.If you have a super capacity memory card, use NDS in the futurepeogrammerOr useMemory stickThe vest or other friends can throw anything into it at will, but its data security performance is not clear for the time being.This SDXC memory card usesNANDFlash memory chip, using Microsoft's[4]ExFAT file system（vistaNew file system).
(2) It supports UHS 104, a new ultra high speed SD interface specification, and the highest standard of the new SD memory card standard Ver.3.00. It can achieve a bus transmission speed of 104MB/s on the SD interface, thus achieving a maximum write speed of 35MB/s and a maximum write speed of 60MB/sMaximum reading speed。
(3) UHS104 provides a traditional SD interface - 3.3V DS (25MHz)/HS (50MHz). The new SDHC memory card supporting UHS104 is compatible with existing SDHC corresponding devices.
(4) The SDXC memory card is only compatible with the SDXC corresponding device equipped with the exFAT file system.It cannot be used for SD or SDHC corresponding equipment.
(6) UHS104 is a new ultra high-speed interface specification,data bustransmission speed Is 104MB per second.This is a new SD memory card[5]The highest standard in Ver.3.00.
(7) SDXC memory card is the next generation SD memory card standard defined by the SD Association in April 2009Storage mediaThe growing demand forData transmission rate。Compared with the SDHC memory card standard that provides 4GB to 32GB capacity, the new SDXC memory card standard can achieve a capacity of more than 32GB, up to 2TB（TB：terabyte, trillion bytes, 1TB=1024GB).
Memory stick
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Memory Stick Card
Memory stickMS isSonyThe memory card product launched by the company in 1999 looks likeChewing gum, length and commonAA batterySame, weight is only 4g.It adopts 10 pin interface structure and has built-in write protection switch.According to the color of the shell, the memory stick can also be blue and white.The white stripe memory stick has the MagicGate copyright protection function, which is commonly used formedia player 。Sony has a very rich digital product line, which makes memory stick widely used. Memory stick has been widely used inDigital camera、PDAandDigital video cameraProducts.
Since other manufacturers have introduced faster and smaller memory cardsSonyIn addition, it has also launched extended and upgraded products of Memory Stick, including MS PRO,MS Duo，MS PRO Duo ， MS Micro，Compact Vault。The memory stick family is really dazzling.
MS PRO
It is called enhanced memory stick, with a size of 50 × 21.5 × 2.8mm, a maximum transmission speed of 160Mbps and a maximum capacity of 32GB.Please note that Memory Stick Pro is not backward compatible with the original memory stick, soBuy productsYou must see whether this type of memory stick is supported.This stick has been widely used in Sony digital cameras since 2003.
MS Duo
It's called a pocket memory stick（Stub）, size 20 × 31 × 1.6mm, volumeSpecific standardThe total amount of MS Duo is only 2g.The maximum write speed is 14.4Mbps,Maximum reading speed19.6Mbps.
MS PRO Duo
This is a new version of MS Duo, with a size of 20 × 31 × 1.6mm. It also supports MagicGate copyright protection technology, and the transmission speed is up to 20MB/S.The stick is widely used in Sony digital camerasSony Digi-Beta on steady-cam 、Sony EricssonMobile phones andPSPOn.MS Duo can be connected to standard MS products through an adapter for use. It is suggested that when purchasing MS PRO memory sticks, you can also consider purchasing MS PRO Duo short sticks for use in more digital products.
MS Micro（M2）
A very compact memory card, mainly designed for mobile phones, launched in February 2006.The size is 15 × 12 × 1.2mm, which is only a quarter of that of MS PRO Duo.It supports 1.8V and 3.3V dual voltages.
Compact Vault
Sony andSeagateCooperative R&DCompatible with CF Ⅱ memory card standardMicrohard diskProducts.At present, the maximum capacity has reached 8GB, which can store 2560 pictures of about 3MB size or 320 minutesMP4。
PCIe flash card
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Flash card（Flash Card）[6]It uses Flash Memory technology to achieve storageElectronic informationOfstorage, generally used in digital cameras,Pocket PCMP3 and other small digital products are used as storage media, so they are compact and like a card, so they are called flash memory cards.PCI-e flash memory card（PCI-Express）Is the latest bus andInterface standard, its original name is "3GIO", PCIe belongs to high-speed serial point-to-pointDual channelHigh bandwidth transmission. The connected devices are allocated with exclusive channel bandwidthshared resource, mainly supporting initiativePower management，Error Reporting, end-to-end reliable transmission,[7]Hot plugas well asService quality(QOS) and other functions.
Its principle is based on[8]【NANDType flash memory], basic memory and NOR type flash memoryStorage unitIt is a bit. Users can access any bit information randomly.The basic storage unit of NAND flash memory is page (as you can see, the page of NAND flash memory is similar to that of hard diska sector, one sector of the hard disk is 512 bytes).The effective capacity of each page is a multiple of 512 bytes.The so-called effective capacity is used fordata storage In fact, 16 bytes of verification information should be added to the part oftechnical informationSee the representation of "(512+16) Byte".The vast majority of NAND flash memory with a capacity below 2Gb is (512+16) bytes of page capacity, while NAND flash memory with a capacity above 2Gb expands the page capacity to (2048+64) bytes.
PCIePCI-SIG(PCI Special Interest Organization) changed its name to“PCI-Express”，It is called "PCI-E" for short.This new standard will completely replace the current PCI andAGP, finally realizedBus standardUnification of.It is mainly used in SSDs (solid stateDriver）In, there are many suppliers of PCIe flash memory cards, such as IBM-TMSIntel、LSI、OCZ、、Samsung(Planned), SanDisk, STEC, SuperTalent, and Toshiba (Planned), among which LSI products are the most prominent, with the best quality and performance.At present, the latest version is PCI-E 3.0, and there are also PCI-E (version 1.0) that have not been delisted.The bandwidth of 2.0 is twice that of 1.0, and that of 3.0 is twice that of 2.0, which is 5GHz x 4.PCI Express 2.0The standard mainly makes a major upgrade in data transmission speed, that is, from the previous 2.5GbpsBus frequencyDouble to 5.0Gbps, which means that the previous PCI Express 2.0 x16 interface can double to an astonishing 10GB/sBus bandwidth（1GB/s=8Gbps）。
Other cards
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CF card
CF card
CF cardIt is one of the memory cards with a long history in the market,storage capacity Large, low cost,compatibilityGood. These are the advantages of CF card, but the disadvantage is its large size.It was created by the United StatesSanDisk、Hitachi、ToshibaIngentix, GermanyPanasonicWhen the 5C Alliance was first launched in 1994, it hasCanon、LG、Epson、CASIO、Minolta、Nikon 、KodakNEC, Polaroid, PanasonicPsion、HPAnd so onOEMUsers, partners and manufacturers have a solid foundation.
CF cardIt is composed of control chip and memory module. The interface adopts 50 pin design. It can be divided into CF Ⅰ and CF Ⅱ, and the latter is twice as thick as the former.Only CF I cardDigital cameraCF II card is not supported, and CF II card camera canBackward compatibilityCFⅠ。 Canon and Nikon's digital cameras areCF memory cardAndDigital SLR cameraAlmost all use CF cards asstorage medium 。
Although CF has been introduced for a long time, it still exudes vitality. Many CF type memory cards with large capacity and small volume have been introduced, includingIBMAnd Hitachi's Microdrive family (MD)Memory chipBut withMicro hard diskAs a storage medium, MD, compared with CF carddurabilityIn particular, the seismic performance is inferior, but MD has the advantages of high capacity and high cost performance.
In addition, likeSandiskMajor manufacturers have also developed CF cards with a capacity of up to 120G. These super capacity CF cards have full play in professional digital cameras.
Digital cameraCF memory cardMedium,Access speedThe symbol of is ×, where "1 ×"=150KB/s, for example: 4 × (600KB/s), 8 × (1.2MB/s), 10 × (1.5MB/s), 12 × (1.8MB/s). Now there are CF memory cards with a maximum of 40 ×.Relatively speaking, the use of faster CF cards will improve the shooting effect of digital cameras. However, some medium and low-end digital camera products in practical applications are due toCCDPhotosensitive sensor, components used, and technical reasons, even if a higher speed CF memory card is used, the speed advantage is difficult to reflect.It is suggested that high-end digital camera users can consider choosing a high-speed CF memory card to speed up the access speed and ensure the shooting effect.
In CF memory card, different manufacturers usually adopt somePatent technology, optimize the read/write speed of digital cameras and memory cards, such asLexarThe company's write acceleration technology (WA) enables digital cameras to have fastertransmission speed Reduce redundant commands, especially for high-resolution digital cameras, by shortening the shooting timeimage fileThe writing speed of is 50%, which optimizes the application in continuous shooting mode.
XD-Picture Card
XD image card is Fuji andOLYMPUSOptical industry developmentSM cardAs a follow-up product of, this card is 20.0 x 25.0 x 1.7 mm in size and weighs only 3 grams. It is also one of the smallest and lightest memory cards at present.
All digital cameras launched by Fuji and Olympus after 2003 use xD memory cards as media.XD Picture Card is named after "eXtreme DigitalImage memoryTechnology).Its reading speed is up to 5MB/Sec, and its writing speed is up to 3MB/Sec (specification: above 64MB).The power consumption is only 25mW.
SM card
The SM (Smart Media) card is created byToshibaThe Flash Memory memory card released in November 1995,SamsungIn 1996, the company purchased the production and sales license, and these two companies became the mainSM cardmanufacturer.SmartMedia card is also a common micro memory card in the marketMP3 playerIt is very popular.
The size of the SM card is 37mm × 45mm × 0.76mm. Because the SM card itself has no control circuit and is made of plastic (divided into many slices), the size of the SM card is small, very thin, and widely used in Olympus and Fuji digital cameras before 2002.But because the control circuit of the SM card is integrated in theElectronicsAmong them (such as digital cameras), this makes the compatibility of digital cameras vulnerable.
It is hard to see its existence in the market.
Other information
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Purpose of memory card
1. Used to store photos on digital cameras.
2. It is used to store music, files, movies and videos on mobile phones.
Pay attention to the following points when purchasing a memory card:
1. Compatibility
Just like DIYComputer hardwareSimilarly, the memory card has compatibility problems.There are also some incompatibilities between different brands of memory cards and digital cameras.It is mainly manifested in the long time to read the card, the long access speed, or the crash.So when you buy a memory card, you must remember the memory card model of the machine.It is safer to take the machine with you to try it.
2. Packaging and appearance workmanship
Pay attention to whether the printing quality of the package is clear and whether there issecurity label If you can use 800 to check the authenticity, you'd better call and ask, and finally check the overall manufacturing condition of the card, whether there is deformation, concavity, crack, and edge of the cardBurrAnd whether the chamfer is symmetrical.
3. Warranty period
Ordinary inferior brands are only for one yearWarrantyHowever, major manufacturers such as SANDISK generally provide a five-year warranty, so when you purchase a machine, you must ask for the warranty time of the memory card you purchased, and ask for the relevant invoice receipt.6. Memory card is suitable for mobile phones, etcMobile DevicesGenerally 1G.2G.4G.8G.16G.32G.
