These cards were the first commercially available on the consumer market. The number of standards started to grow rapidly, as well as the number of supported devices, and we shall make a review of all currently used ones. Let’s set off with two of the oldest and their subspecies, and those are Compact Flash and Secure Digital cards.

Compact Flash 

Compact Flash or CF cards exist in two forms, Type I and Type II. The visual difference is only in their width – Type I has a width of 3.3 mm, whereas Type II is exactly 5 mm wide. Compact Flash cards were first manufactured by SanDisk back in 1994, and it was this American corporation that created official product specifications for this still widely used standard, which are valid even nowadays. However, that doesn’t mean that Compact Flash Type I hasn’t changed dramatically in terms of its capabilities since then. There were four stages in the CF evolution. These refer primarily to its speed, while the rest of the characteristics remained largely unaffected. The last and fastest one of these is, unsurprisingly, the CF 4.0 standard, officially accepted in the beginning of 2007. Compact Flash memories are significantly larger than its counterparts, so they are only used in bigger devices. However, CF managed to outlive Miniature Card, Smart Card and other standards. CF card speeds are marked just like CD-ROM ones: 20X, 133X etc. The multiplier represents multiplied speed of 150 KB/s (1X). The first generation had a transfer of just over 1 MB/s, whereas the cards of today have a theoretical speed of 133 MB/s. On the practical side of things, the fastest currently available models have a speed of 333X, i.e. around 50 MB/s. Just like the speeds of CF cards vary a lot, so do the available capacities. The models currently in offer range from 512 MB all the way to an impressive 64 MB. Even though this card type can be formatted to any format, the most usual file systems are FAT16 and FAT32. Compact Flash Type II is a less successful type of CF cards, since it is far rarer and used only in Microdrive devices, which are in fact small hard drives. These small devices consume far more power than Type I cards. An average Microdrive has a power consumption of 500 mA, which is five times more than flash-based cards (100 mA). The strongest pros of the CF standard are longevity and survival on the market (mostly owing to professional photographers, which deem this standard irreplaceable), universality, versatility (SATA-interfaced CF cards were introduced this year), and the fact that this standard is considered very resistant to physical strain. Besides, this memory standard is also free of any DRM (Digital Rights Management) and cryptographic protection, which is also a positive feature for the end-user.

 MMC

MMC is an abbreviation of Multi-Media Card and represents a standard first introduced in 1997 as a product of joint research by Siemens and SanDisk. The product reached instant popularity the moment it first appeared, because it was based on Toshiba’s NAND flash memory, unlike the CF cards, which meant significantly smaller dimensions. This was a crucial selling point at that moment. Its speed, however, didn’t manage to keep up with the later introduced Secure Digital standard, so MMC is very scarce today. However, this memory standard is far from extinct, mostly due to its one-way compatibility with SD – MMC card works flawlessly inside an SD slot, but not vice versa. MMC is primarily used in portable devices such as mp3/mp4 players, mobile phones, even certain photo-cameras, although SD is a more preferable standard for images (because of MMC’s limited speed). MMC spawned a number of sub-variants, such as RS-MMC (Reduced Size MMC), which was licensed by Nokia and Siemens and used in their mobile phones until recently (Symbian S60 v1-based phones). Other characteristics were exactly the same, so RS-MMC could use a small add-on to be extended to full MMC format (very useful for inserting in card readers).The next step in MMC evolution was the DV-MMC (Dual Voltage MMC), which could operate on two different voltages, 1.8 V and 3.3 V. A voltage of 1.8 V greatly decreases power consumption, which implies a better working autonomy of devices with DV-MMC inside. This was an important new feature to all portable devices. However, this standard went largely unnoticed, as newer standard were introduced shortly thereafter. MMCplus and MMCmobile brought higher speeds (26 and 52 MHz, as opposed to MMC’s 20 MHz) and a wider bus (4 and 8 bits as opposed to 1 bit, respectively). These were the last two significant improvements of the MMC standard. Although MMCmicro and SecureMMC appeared to late, the latter of which even tried to compete with SD, no noticeable success was achieved. SecureMMC is new standard and it should integrate DRM protection.

 Secure Digital

Secure Digital is a memory standard first developed by Matsushita, SanDisk and Toshiba. The concept of these cards is similar to that of the MMC cards - to be ideal for portable devices. The capacity of these cards varies between 8 MB and 2 GB, with SDHC even reached an 8 GB capacity. SDHC is an abbreviation of Secure Digital High Capacity and cards bearing this logo first appeared in June 2006. This new type of SD cards is generally compatible with the ordinary SD standard, although older devices have been known to have problems with SDHC. The basic difference is that it uses a different addressing method, which enables a greater capacity. Design-wise, the SD standard is no different than the MMC cards, but this is just an illusion. Secure Digital cards enable data encryption and faster data transfers, which enabled the standard to reach a much higher degree of popularity. The SD standard was created to calm down the music industry, one traditionally against the MMC standard (it made piracy easy, as they say). SD came in right on time, since it had the encryption possibilities to add to the DRM, although this feature turned out to be used extremely scarcely. However, all the advancements created a redundancy in some very old devices from the 1st SD generation era. They might either not recognize the card at all, or recognize only a certain amount of its capacity. If you are having doubts about a new mobile phone, camera or mp3 player, make sure you check the specifications concerning the maximum supported memory quantity. Should you not be unable to find this information, ask to check the memory card on the spot in the specified device to avoid any further concern. SD cards also have two subtypes, miniSD and microSD, aka TransFlash (T-Flash). These two standards, reduced in size, only further extended the reach of this standard.

 xD Picture Card

xD Picture Card is a standard that had only a single use ever since it was first manufactured, and that is – digital camera image storage. xD is an abbreviation of eXtreme Digital, and was developed by Fuji and Olympus. They were introduced in June 2002, and manufactured by Samsung Electronics and Toshiba. Brands such as Kodak, SanDisk and Lexar also use this standard these days. Beside their primary purpose, they are also used in digital dictaphones by Olympus. The size of these cards is their greatest strength. Although they haven’t changed a bit since 6 years ago, they are very small even by today’s standards – 20x25x1.78 mm. Capacity varies between 8 MB and 2 GB, while the transfer speeds are very low, even below MMC level. There are M- and H-type xD cards. The M-type is slower and was first presented in the beginning of 2005, but was replaced by H-type by the end of the year. The H-type cards have a lower theoretical maximum capacity, but are somewhat faster than the M-type cards. The popularity of these cards never reached too high, mostly because of their limited applicability – a small number of supported devices, few manufacturers and low speed. However, small dimensions and low power consumption makes these cards interesting and usable even today.

The Memory Stick is Sony’s response to other universal memory standards. Decidedly against making their products universally compatible (and also keen to earn a few more bucks), Sony created a unique memory extension for their own devices. The Memory Stick was launched in 1998, and went through a number of iterations since. It all began with the original Memory Stick, which kept its name throughout the forthcoming generations. The first series was mostly used in cameras and covered capacities ranging from 8 to 128 MB. A new, Select version of the MS was launched a tad later, containing two physical memory sticks in one casing and providing a capacity of 256 MB. The MS Pro version followed suite, with a larger capacity and higher read/write speeds, but keeping the original physical characteristics still. This standard was often the only option for owners of Sony cameras eager to record video in maximum resolution. This was followed by the MS Duo (Pro) version, which was reduced in size, but still compatible with the previous generations. Transfer speed, capacity and usability were increased even further. The MS Duo is now used in Sony cameras, mp3 players, mobile phones, Sony PlayStation Portable handheld gaming consoles etc. Following the worldwide trends, Sony was quick to reply to the challenge in form of microSD cards by creating the M2. This is the latest Sony’s offering, and we must admit that it is just as fast as it is tiny. It even has a minimal speed requirement, making it compatible with AVCHD (Advanced Video Codec High Definition) products. You will also find an M2 card bundled with all newer Sony Ericsson mobile phones.

A full deck of cards

Don’t let this number of available standards and subtypes confuse you! We are sure that you’ve already met at least some of these. They are all around us, in consoles, cameras, mp3 players, mobile phones and a great deal of other devices. They are a part of everyday life just as any other digital device, and as far as our advice is concerned, there is only one thing to suggest – try to maintain as many of your devices as possible compatible with a single memory standard.

Discuss this article on the forums. (0 posts)