A £5 SD card from a supermarket will give you the same results as using the latest generation of card from Lexar, SanDisk or Samsung. The difference, however, is that the cheaper card may do it much more slowly, be less reliable, have fewer backup measures, different components, and, in terms of memory card data recovery, may not be such a wise choice if things go wrong and your images go missing.
At 2.2 inches wide, the Unitek is a little broader than all of our other picks (even the bulky Kingston USB 3.0 High-Speed Media Reader), but it’s only 2.4 inches long, around a half inch shorter than most of the competition. It also comes with a white, 12-inch connecting cable attached to its back. It’s easily pocketable and very light at 2.2 ounces, and its glossy silver finish makes it better-looking than some of the other card readers we’ve tested.
SDHC cards are physically and electrically identical to standard-capacity SD cards (SDSC). The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card-Specific Data (CSD) register in version 2.0 (see below), and the fact that SDHC cards are shipped preformatted with the FAT32 file system.
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.
Many ASICs are pad-limited, meaning that the size of the die is constrained by the number of wire bond pads, rather than the complexity and number of gates used for the device logic. Eliminating bond pads thus permits a more compact integrated circuit, on a smaller die; this increases the number of dies that may be fabricated on a wafer, and thus reduces the cost per die.
In flash memory, each memory cell resembles a standard MOSFET, except that the transistor has two gates instead of one. On top is the control gate (CG), as in other MOS transistors, but below this there is a floating gate (FG) insulated all around by an oxide layer. The FG is interposed between the CG and the MOSFET channel. Because the FG is electrically isolated by its insulating layer, electrons placed on it are trapped until they are removed by another application of electric field (e.g. Applied voltage or UV as in EPROM). Counter-intuitively, placing electrons on the FG sets the transistor to the logical “0” state. Once the FG is charged, the electrons in it screen (partially cancel) the electric field from the CG, thus, increasing the threshold voltage (VT1) of the cell. This means that now a higher voltage (VT2) must be applied to the CG to make the channel conductive. In order to read a value from the transistor, an intermediate voltage between the threshold voltages (VT1 & VT2) is applied to the CG. If the channel conducts at this intermediate voltage, the FG must be uncharged (if it was charged, we would not get conduction because the intermediate voltage is less than VT2), and hence, a logical “1” is stored in the gate. If the channel does not conduct at the intermediate voltage, it indicates that the FG is charged, and hence, a logical “0” is stored in the gate. The presence of a logical “0” or “1” is sensed by determining whether there is current flowing through the transistor when the intermediate voltage is asserted on the CG. In a multi-level cell device, which stores more than one bit per cell, the amount of current flow is sensed (rather than simply its presence or absence), in order to determine more precisely the level of charge on the FG.
If you still need a USB-A card reader for your older computer, or you’re a photographer who wants a reader that can take both CF cards and high-speed UHS-II SD cards, the Kingston USB 3.0 High-Speed Media Reader is your best bet. The Kingston supports SD, microSD, CF, and Memory Stick cards, and it reliably transferred data at UHS-II speeds in our SD card tests. It also has a big red indicator light, and comes with a two-year warranty.
Cards that comply with UHS show Roman numerals ‘I’, ‘II’ or ‘III’ next to the SD card logo, and report this capability to the host device. Use of UHS-I requires that the host device command the card to drop from 3.3-volt to 1.8-volt operation over the I/O interface pins and select the four-bit transfer mode, while UHS-II requires 0.4-volt operation.
After spending eight hours researching and testing 12 card readers, we found that the IOGear USB-C 3-Slot Card Reader is the best option for anyone who needs an SD card reader for a new laptop with USB-C ports. The IOGear delivered fast, consistent speeds, and supports SD, microSD, and CF cards.
xD Picture cards (standing for ‘eXtreme Digital’) are a Fujifilm format used in some (older) Fuji and Olympus cameras, although these brands are now routinely compatible with more standard SD/SDHC technology.
Partnering with Nintendo in 1998, ArtX began the complete design of the system logic and of the graphics processor (codenamed “Flipper”) of Nintendo’s sixth generation video game console, reportedly bearing the early internal code name of “N2000”. At Nintendo’s press conference in May 1999, the console was first publicly announced as “Project Dolphin”, the successor to the Nintendo 64. Subsequently, Nintendo began providing development kits to game developers. Nintendo also formed a strategic partnership with IBM for the production of Dolphin’s CPU, code-named “Gekko”.
The trademarked SD logo was originally developed for the Super Density Disc, which was the unsuccessful Toshiba entry in the DVD format war. For this reason the D within the logo resembles an optical disc.
Although Tripp Lite’s USB 3.1 USB-C Multi-Drive Flash Memory Media Reader has similar speeds to the Unitek, its microSD port suffers from the same misalignment as the one on our runner-up pick, it’s missing an indicator light, and it costs nearly twice as much as the Unitek.
As of 2013, V-NAND flash architecture allows read and write operations twice as fast as conventional NAND and can last up to 10 times as long, while consuming 50 percent less power. They offer comparable physical bit density using 10-nm lithography, but may be able to increase bit density by up to two orders of magnitude.
The NAND type operates primarily in memory cards, USB flash drives, solid-state drives (those produced in 2009 or later), and similar products, for general storage and transfer of data. NAND or NOR flash memory is also often used to store configuration data in numerous digital products, a task previously made possible by EEPROM or battery-powered static RAM. One key disadvantage of flash memory is that it can only endure a relatively small number of write cycles in a specific block.
The SanDisk Extreme Pro UHS-II Card USB-C Reader was our previous recommendation for UHS-II speeds, but it costs nearly three times as much as the Verbatim, and it doesn’t have a microSD slot. Its SD card read and write speeds were about 39 MB/s and 31 MB/s faster than the Verbatim’s, though, and it has a useful indicator light and a simple design.
Reliability and warranty: It’s vital that a card reader works the way it’s meant to. We tested a surprising number of units in this category that were defective or performed inconsistently. For this reason, we favor readers from trustworthy manufacturers with solid warranties—most USB-C card readers that we found had one-year warranties, but two- and three-year warranties are even better.
An SD Card (Secure Digital Card) is an ultra small flash memory card designed to provide high-capacity memory in a small size. SD cards are used in many small portable devices such as digital video camcorders, digital cameras, handheld computers, audio players and mobile phones. In use since 1999, SD Memory Cards are now available in capacities between 16 Megabytes and 1 Gigabyte. An SD card typically measures 32 x 24 x 2.1 mm and weighs approximately 2grams.
Consumer-grade solid-state drives (SSDs) embed silicon-based memory chips as storage media for persistent storage of data. The earliest SSDs were generally designed for consumer devices. The debut of the Apple iPod in 2005 marked the first notable flash-based device to broadly penetrate the consumer market. SanDisk has a line of portable SSDs that scale to 1.92 terabytes (TB) of flash capacity; they are marketed mainly for flash storage of digital photography.
microSD is a type of removable flash memory card used for storing information. SD is an abbreviation of Secure Digital, and microSD cards are sometimes referred to as µSD or uSD. The cards are used in mobile phones and other mobile devices.
Although flash memory is technically a type of EEPROM, the term “EEPROM” is generally used to refer specifically to non-flash EEPROM which is erasable in small blocks, typically bytes. Because erase cycles are slow, the large block sizes used in flash memory erasing give it a significant speed advantage over non-flash EEPROM when writing large amounts of data. As of 2013, flash memory costs much less than byte-programmable EEPROM and had become the dominant memory type wherever a system required a significant amount of non-volatile solid-state storage.
The Cable Matters reader has similar speeds to the Unitek and Iogear readers. During our SD card tests, the Cable Matters reader had a read speed of 92 MB/s and a write speed of 86 MB/s. When we tested the unit with a microSD card, it had a read and write speed of 92 MB/s and 71 MB/s, respectively. The Cable Matters can also read two cards simultaneously, like our top pick, though its speeds drop sharply. Running an SD and a microSD card at the same time gave us abysmal read and write speeds of 19.5 MB/s and 17.2 MB/s from both cards, respectively. The Unitek gave us decent read and write speeds of 59 MB/s and 49 MB/s when transferring data from two cards at once.
A hybrid flash array blends disk and SSDs. Hybrid arrays use SSDs as a cache to speed access to frequently requested hot data, which subsequently is rewritten to back-end disk. Many enterprises commonly archive data from disk as it ages by replicating it to an external magnetic tape library.
Secure Digital cards are ubiquitous in consumer electronic devices and have become the dominant means of storing several gigabytes of data in a small form factor. This new device is extremely compact but big on compatibility within the SD memory card family. The unit supports the very latest in memory card format, SDXC (Secure Digital Extended Capacity).
The Cable Matters USB 3.1 Type-C Dual Slot Card Reader is the best option if you don’t need a CF card reader—it performed just as well as our top picks, and it’s cheaper, too. Though it doesn’t support CF cards, it has slots for both SD and microSD cards, and it can read two cards at once. (Though the Cable Matters loses much more speed than the Unitek when transferring data from both cards concurrently). It’s smaller and lighter than both of our top picks, and like the Unitek, the Cable Matters has an indicator light so you know when it’s in use. It comes with a one-year warranty.
The Video Speed Classes defined by the SD Association are V6, 10,30,60 and 90. V6 and V10 can be applied to High Speed and UHS Bus IF product family. V30 can be applied to UHS Bus IF product family. V60 and V90 can be applied to UHS-II / UHS-III product family.
The SanDisk Standard SD memory card has a blank writeable white space on the front of the card, making it easy to identify your different cards. Use one memory card for all your vacation photos, and another for all your favorite music–the label makes it easy to see which is which at a glance. Rather than inserting cards into your digital device to review the content, simply look at the label and go.
SDHC card: This card has the same form factor as an SD card, with specifications that define SDHC card capacities from 4 GB to 32 GB. These devices were developed to tackle high-definition video and high-resolution images. Although SD cards will work in an SDHC device, an SDHC card will not function in an SD card-based digital camera or card reader.
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.
However, SD is much more open than Memory Stick, for which no public documentation nor any documented legacy implementation is available. All SD cards can be accessed freely using the well-documented SPI bus.
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The Unitek was fast and stable when we tested its SD, microSD, and CF speeds—many other readers gave us inconsistent results or didn’t work at all. The Unitek can also read two cards simultaneously—although you lose some speed when transferring data from both cards at once. It doesn’t support UHS-II speeds, but there aren’t any USB-C readers that support both CF and UHS-II SD cards yet. The Unitek is small and light, with a long attached cable and a useful indicator light so you can see when your card is connected or transferring data. It comes with a two-year warranty, about the same as its competitors.
I haven’t really been able to find reviews for this reader that thoroughly address the issue of car connectivity [and I’ll admit I gave a few a quick once-over and was just trying to key in on a few words]. I bought this item on a gamble because of that. I figured that for the price, if it wouldn’t work with my car, I can always find another use for it, with barely a dent in my wallet.
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.
Bought this for me and my wife shortly after we bought a GameCube (to relive our childhood) a little less than 2 years ago. So far it has worked flawlessly with all games played, and is not even close to filling up. Item received was slightly different in shape than the picture advertised, but that is purely aesthetic.
Jump up ^ Masuoka, F.; Momodomi, M.; Iwata, Y.; Shirota, R. (1987). “New ultra high density EPROM and flash EEPROM with NAND structure cell”. Electron Devices Meeting, 1987 International. IEEE. Archived from the original on 14 May 2013. Retrieved 4 January 2013.
A joint development at Intel and Micron will allow the production of 32-layer 3.5 terabyte (TB) NAND flash sticks and 10 TB standard-sized SSDs. The device includes 5 packages of 16 × 48 GB TLC dies, using a floating gate cell design.
If our pick is sold out or unavailable, the Iogear USB-C 3-Slot Card Reader is a good second choice. Like our top pick, the Iogear delivers fast speeds with SD, microSD, and CF cards, although it can read only one card at a time. The Iogear is a little longer than the Unitek, but it’s thinner and lighter, with a shorter connecting cable. It lacks an indicator light, though, and its slots weren’t as easy to use as the Unitek’s. Using the Iogear’s CF card slot, in particular, isn’t intuitive. We spent 30 seconds trying to fit the CF card into its slot—risking damage to the card and the slot—before realizing that it had to be inserted upside down relative to the logo and the other slots. The Unitek’s slots, on the other hand, recognized every card right-side up. The Iogear comes with a three-year warranty, longer than that of any of its competition.
The SD protocol envisioned the ability to gang 30 cards together without separate chip select lines. The host device would broadcast commands to all cards and identify the card to respond to the command using its unique serial number.
Additionally, as with live USB flash drives, an SD card can have an operating system installed on it. Computers that can boot from an SD card (either using a USB adapter or inserted into the computer’s flash media reader) instead of the hard disk drive may thereby be able to recover from a corrupted hard disk drive. Such an SD card can be write-locked to preserve the system’s integrity.
To erase a NOR flash cell (resetting it to the “1” state), a large voltage of the opposite polarity is applied between the CG and source terminal, pulling the electrons off the FG through quantum tunneling. Modern NOR flash memory chips are divided into erase segments (often called blocks or sectors). The erase operation can be performed only on a block-wise basis; all the cells in an erase segment must be erased together. Programming of NOR cells, however, generally can be performed one byte or word at a time.