Like most memory card formats, SD is covered by numerous patents and trademarks. Royalties for SD card licences are imposed for manufacture and sale of memory cards and host adapters (US$1,000/year plus membership at US$1,500/year), but SDIO cards can be made without royalties.
Getting yourself in a memory card muddle and not sure which card to buy? We look at memory card speeds and the fastest memory card on the market to help explain the differences so you can find out what’s the best card for you.
Antony Adshead, a storage editor with Computer Weekly, explains the basics of flash storage technology and offers a rundown of MLC, eMLC, SLC and TLC flash, commenting on their place in the market and the use cases they are suited to.
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In the definition of SDHC cards in version 2.0, the C_SIZE portion of the CSD is 22 bits and it indicates the memory size in multiples of 512 KB (the C_SIZE_MULT field is removed and READ_BL_LEN is no longer used to compute capacity). Two bits that were formerly reserved now identify the card family: 0 is SDSC; 1 is SDHC or SDXC; 2 and 3 are reserved. Because of these redefinitions, older host devices do not correctly identify SDHC or SDXC cards nor their correct capacity.
SanDisk Ultra CompactFlash memory cards deliver the ideal combination of reliability, value, and performance for casual photographers with entry to mid-range DSLRs. Capture the moment with ultra fast shot speeds and save time moving files to your computer with transfer speeds of up to 50MB/s1 (8GB – 32GB2). For dependability and solid performance, you can count on SanDisk Ultra CompactFlash memory cards to capture and store your favorite pictures and videos. That’s why for memories that can’t be missed, photographers worldwide choose SanDisk..
mSATA flash drives mainly used in laptops, netbooks and other portable computing devices. The mSATA specification maps SATA signals to an internally mounted PCIe card in a computer motherboard. The M.2 SSD form factor for ultrathin computing devices is generally considered to be the eventual replacement for mSATA-based flash memory cards.
The speed class rating was based on request from movie and video companies, as video recording in different formats and resolutions requires certain write speeds when recording to the card. As a result, the goal of the class ratings is to allow consumers to easily identify cards that meet the minimum level of required performance based on their use or application of the host device. Below is a listing of typical applications for each speed class.
Also in early 2010, commercial SDXC cards appeared from Toshiba (64 GB), Panasonic (64 GB and 48 GB), and SanDisk (64 GB). In early 2011, Centon Electronics, Inc. (64 GB and 128 GB) and Lexar (128 GB) began shipping SDXC cards rated at Speed Class 10. Pretec offered cards from 8 GB to 128 GB rated at Speed Class 16.
Cards often have a multiplication factor written on them which usually represents read speed (such as 133x, 200x, 300x, etc). This is called the ‘Commercial x rating’ with 1x being equivalent to the speed of the original CD-ROM of 150 KB/sec. This makes it easy to convert between the two by multiplying or dividing by 150. So, 200x will equate to 1 seconds to read a 29.5MB image file (200 x 150 = 30,000/1016 = 29.528).
Many games released on the GameCube, such as Pikmin and Chibi-Robo! later became popular Nintendo franchises, while also spawning multiple sub series, such as the Metroid Prime series, and Luigi’s Mansion.
PC Cards (PCMCIA) were the first commercial memory card formats (type I cards) to come out, but are now mainly used in industrial applications and to connect I/O devices such as modems. Since 1994, a number of memory card formats smaller than the PC Card arrived, the first one was CompactFlash and later SmartMedia and Miniature Card. The desire for smaller cards for cell-phones, PDAs, and compact digital cameras drove a trend that left the previous generation of “compact” cards looking big. In digital cameras SmartMedia and CompactFlash had been very successful[neutrality is disputed]. In 2001, SM alone captured 50% of the digital camera market and CF had captured the professional digital camera market. By 2005 however, SD/MMC had nearly taken over SmartMedia’s spot, though not to the same level and with stiff competition coming from Memory Stick variants, as well CompactFlash. In industrial and embedded fields, even the venerable PC card (PCMCIA) memory cards still manage to maintain a niche, while in mobile phones and PDAs, the memory card has become smaller.
The companies also formed the SD Association (SDA), a non-profit organization, in January 2000 to promote and create SD Card standards. SDA today has about 1,000 member companies. The SDA uses several trademarked logos owned and licensed by SD-3C to enforce compliance with its specifications and assure users of compatibility.
Professionals should also look at how reliable a card is as you can’t take the risk of losing all your photos. This can be worked out by Mean Time Before Failure (MTBF). SanDisk claims a MTBF of over 1,000,000 hours for its memory cards – that’s almost 115 years before the average card is expected to fail.
The GameCube introduced a proprietary miniDVD optical disc format as the storage medium for the console, capable of storing up to 1.5 GB of data. The technology was designed by Matsushita Electric Industrial (now Panasonic Corporation) which utilizes a proprietary copy-protection scheme – different from the Content Scramble System (CSS) found in standard DVDs – to prevent unauthorized reproduction. The Famicom Data Recorder, Famicom Disk System, SNES-CD, and 64DD had explored various complementary storage technologies, but the GameCube was Nintendo’s first console to move away from cartridge-based media altogether. The GameCube’s 1.5 GB mini-disc have sufficient room for most games, although a few games require an extra disc, higher video compression, or removal of content present in versions on other consoles. By comparison, the PlayStation 2 and Xbox, also sixth-generation consoles, both use 8.5 GB Dual-Layer DVDs.
Like other types of flash memory card, an SD card of any SD family is a block-addressable storage device, in which the host device can read or write fixed-size blocks by specifying their block number.
In February 2014, SanDisk announced a new microSD card, the MicroSDXC. At the time, the cards held up to 128GB. To enable this amount of storage capacity on a removable microSD card, SanDisk developed a proprietary technique that allows for 16 memory die to be vertically stacked, each shaved to be thinner than a strand of hair. At the time of their release, these cards had capacities ranging from 8GB to 128GB, with the prices ranging from $29.99 to $199.99. 
In 1999, SanDisk, Matsushita, and Toshiba agreed to develop and market the Secure Digital (SD) Memory Card. The card was derived from the MultiMediaCard (MMC) and provided digital rights management based on the Secure Digital Music Initiative (SDMI) standard and for the time, a high memory density.
The specific commands used to lock, unlock, program, or erase NOR memories differ for each manufacturer. To avoid needing unique driver software for every device made, special Common Flash Memory Interface (CFI) commands allow the device to identify itself and its critical operating parameters.
Windows Phone 8 devices use SD cards designed for access only by the phone manufacturer or mobile provider. An SD card inserted into the phone underneath the battery compartment becomes locked “to the phone with an automatically generated key” so that “the SD card cannot be read by another phone, device, or PC”. Symbian devices, however, are some of the few that can perform the necessary low-level format operations on locked SD cards. It is therefore possible to use a device such as the Nokia N8 to reformat the card for subsequent use in other devices.
Integrated Wi-Fi – Several companies produce SD cards with built-in Wi-Fi transceivers supporting static security (WEP 40; 104; and 128, WPA-PSK, and WPA2-PSK). The card lets any digital camera with an SD slot transmit captured images over a wireless network, or store the images on the card’s memory until it is in range of a wireless network. Examples include: Eye-Fi / SanDisk, Transcend Wi-Fi, Toshiba FlashAir, Trek Flucard, PQI Air Card and LZeal ez Share. Some models geotag their pictures.
Due to its relatively simple structure and high demand for higher capacity, NAND flash memory is the most aggressively scaled technology among electronic devices. The heavy competition among the top few manufacturers only adds to the aggressiveness in shrinking the design rule or process technology node. While the expected shrink timeline is a factor of two every three years per original version of Moore’s law, this has recently been accelerated in the case of NAND flash to a factor of two every two years.
CompactFlash (CF) cards offer very high storage capacities and fast processing times. They were first introduced by Sandisk in 1994 and were widely used, but now they are usually only found in the most advanced DSLRs. Last year Canon chose CompactFlash as the recording media for use in its new lineup of professional high definiton (HD) video cameras.
USB flash drives are known as the floppy disks of the 21st century. You can see people walking around with them dangling from key chains, backpacks, and even around their necks. These are more resistant to physical abuse than the media cards used in digital cameras.
Bad block management is a relatively new feature in NOR chips. In older NOR devices not supporting bad block management, the software or device driver controlling the memory chip must correct for blocks that wear out, or the device will cease to work reliably.
All SD cards let the host device determine how much information the card can hold, and the specification of each SD family gives the host device a guarantee of the maximum capacity a compliant card reports.
Jump up ^ Zackariasson, Peter; Wilson, Timothy L.; Ernkvist, Mirko (2012). “Console Hardware: The Development of Nintendo Wii”. The Video Game Industry: Formation, Present State, and Future. Routledge. p. 158. ISBN 978-1138803831.
These cards are each pre-packed in a certified Frustration Free Packaging (FFP) mailer labelled Amazon/SanDisk (No. 80-56-10641), and then shipped in a bubble wrap envelope which was 11.25″ x 9″. The bubble envelope seemed too big, but perhaps that size was necessary to accommodate the huge shipping label. I will post some pictures of the package and card.
In July 2016, Samsung announced the 4TB Samsung 850 EVO which utilizes their 256 Gb 48-layer TLC 3D V-NAND. In August 2016, Samsung announced a 32 TB 2.5-inch SAS SSD based on their 512 Gb 64-layer TLC 3D V-NAND. Further, Samsung expects to unveil SSDs with up to 100 TB of storage by 2020.
Integrated USB connector – The SanDisk SD Plus product can be plugged directly into a USB port without needing a USB card reader. Other companies introduced comparable products, such as the Duo SD product of OCZ Technology and the 3 Way (microSDHC, SDHC, and USB) product of A-DATA, which was available in 2008 only.
If you’re planning to store photos and videos on your memory card, you may need to consider write speed as well as capacity. If your photography needs are fairly basic, such as taking clear, quality pictures of family vacations or get-togethers, any average memory card, like a Speed Class 10, should provide sufficient speed and reliability. However, if you plan on taking video including 4K Ultra HD or HRD, you’ll require faster speed and more capacity.
An individual memory cell is made up of one planar polysilicon layer containing a hole filled by multiple concentric vertical cylinders. The hole’s polysilicon surface acts as the gate electrode. The outermost silicon dioxide cylinder acts as the gate dielectric, enclosing a silicon nitride cylinder that stores charge, in turn enclosing a silicon dioxide cylinder as the tunnel dielectric that surrounds a central rod of conducting polysilicon which acts as the conducting channel.
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