MMC. Description and information of MMC. Kingston memory cards with MMC and SD interfaces What is mms micro flash drive

No sooner had we gotten used to cards conforming to the SD 1.1 specification (and most devices still only support the slower SD 1.0), when a transition to SD 2.0 loomed on the horizon. It can be assumed that, as a result, 1.1 becomes a "passable" version, and you shouldn't pay attention to it. In fact, everything is different. There is a feeling that the implementation of SD 2.0 will be even slower and more painful than the transition from 1.0 to 1.1, or even from MMC 3.0 to 4.x. Most likely, this process will resemble the transition from MMC to SD, which, by the way, did not end as a result - instead of the MMC death predicted many times (including by me), this format, on the contrary, has recently found a second wind. The reason is the same - the lack of backward compatibility between SD and SDHC (such a logo will be worn by all cards that meet specifications 2.0). If an SD 1.1 card can be safely used in conjunction with devices designed for SD 1.0 (albeit at a lower speed - as much as possible in 1.0), the same applies to MMC 4.x / 3.0, then the SDHC card will work in "normal" There will be no SD device. Thus, an SD 1.1 or MMCplus card could be bought for the future, but an SDHC card could not. At the same time, SDHC devices will be compatible (when available) with regular SD cards, so the latter can be safely purchased. Not the fact that you will lose something later. Why? Let's see what SD 2.0 brings us.

Just fixing bugs

The transition from SD 1.0 to 1.1 doubled the maximum speed, the transition from MMC 3.0 to 4.0 gave us, in fact, new cards, but what does SD 2.0 give? Officially, there are only two things - an increase in the maximum volume of cards and the Class Speed ​​Rating. The second is simpler, so let's start with it.

As you know, manufacturers prefer to label memory cards according to the maximum read speed, and the theoretically possible one. Not all and not always, but in most cases we observe exactly this. The write speed, if indicated, is also the maximum, and even then not always, and only in the specifications and in small print. And the speed of reading (the notorious "X") is most often indicated directly on the map in arshin (compared to the size of the map itself) letters. However, it is far from always at least close to the write speed (a vivid example is MLC chips, where the difference is several times by definition), and it is difficult to achieve high values ​​of the latter in the case of flash. Manufacturers do not indicate it - it is unprofitable. As a result, the purchased "high-speed" card can easily turn out to be slower than the "regular" one, which we have met more than once. At the same time, in many areas of application, the reading speed is not very important (just think - photos after the vacation will be transferred to the computer in 10 minutes, and not in 5: no one dies), while the write speed is critical. An example is the same cameras, where a low write speed simply does not allow for continuous shooting. The situation is even worse with video recording, where flash is gradually becoming one of the most commonly used media: a low write speed will make shooting simply impossible due to the fact that most frames will "drop out" with an obvious end result. The first attempt to sort out the mess with markings was made by the MMC-alliance: the MMCplus card is not only obliged to support the 4.x specification, but also to have a minimum steady-state write speed of at least 2 MB / s. The SD-association went even further, introducing three classes of cards: Class 2, Class 4 and Class 6. The numbers here are not abstract values, namely, the established minimum write speed - 2, 4 and 6 MB / s. This innovation is useful, but not so vital: our tests show that today the overwhelming majority of even inexpensive cards are quite capable of handling 6 MB / s. On the other hand, it will become easier when buying: for example, if you know that SDHC Class 6 is required to fully realize the capabilities of a photo or video camera, then you should look for such a card without rummaging through the test results and descriptions on the manufacturers' websites. Of course, the possibility of abuse by the manufacturer remains in theory, but in this case he will receive not only grievous lamentations from the deceived user in various forums, but also persecution from the Association, which hardly anyone will do (even from small companies).

As for the volume, the situation is simple and straightforward. Officially, today's SD cards cannot exceed 2GB. The limitation is not physical, but logical: this is due to the used file system - FAT16. The latter also supports volumes of more than 2 GB, but with a non-standard cluster size, which the manufacturers of consumer equipment for the most part will not do. And for SDHC, the official file system is FAT32, so the limitation is almost lifted. However, some upper frames have been included in the standard so far - 32 gigabytes, but up to this capacity compact cards will still grow and grow (and prices will fall and fall :)). In the end, some of the formats support large volumes, but cards of at least 16 GB, let alone 32 or 64, are not yet visible;) So, from this point of view, SDHC is an obvious step forward compared to SD ... However, somewhat blurred by the fact that some hardware manufacturers have already mastered FAT32 support within SD 1.1 as well. And the manufacturers of memory cards responded with the release of SD cards, with a capacity of 4 gigabytes. Such cards, even in our area, already cost less than $ 100. They will subsequently work in equipment with SDHC support (let me remind you that there is compatibility in this direction), and no one will fix devices that do not support such cards anyway, since SDHC will definitely not work in them;)

This is what makes the transition from SD 1.1 to 2.0 unlike the transition from 1.0 to 1.1. In the second case, we could simply buy new cards and wait for the appearance of new devices that would reveal all their capabilities. In the first it is necessary at first wait until the market is saturated with devices with SDHC support, and Then buy cards as they are useless for older devices. Even then, you can still use regular high-capacity SD's as they will work in the future. It is possible that in the present, but it is necessary to check a specific device. So far on the SanDisk website, I have found only seven SDHC-compatible devices with all that it implies. We can say that actively announced in recent times SDHC cards with a capacity of 4 GB are simply useless - you can buy regular ones of this capacity. When you want to get an eight gigabyte card, it's another matter: there will be no SDHC alternatives. But first you need to purchase a device in which you can use such a card.

And how can this affect "popular" volumes up to 2 GB? No - SDHC cards of this capacity are not planned. This segment of the market will remain the domain of SD 1.1, and many users do not even need two gigabytes at the current price level. That is why testing SD 1.1 cards continues to make sense, and this situation can last at least another year, or even more. After the appearance of the specifications of version 4.1, the MMC alliance does not make any sudden movements - first you need to master what the standard already allows (since the latest version of the specification was developed a little later than in the case of a competitor, and it was much more revolutionary than SD 1.1 - in the result is quite standard cards MMC 4.x, with a capacity of 8 GB, have already been announced, and nothing in the standard had to be altered;)). The main interest for us is still represented by cards compatible with SD 1.1 and MMC 4.1. We will study these once again. The topic of today's article is representatives of several lines of flash cards from Kingston, belonging to the two mentioned families. In addition to the manufacturer, they are related, by the way, also the capacity - all by gigabyte. For many applications, it is quite enough, and the price has already dropped to such a level that you can not deny yourself anything;)

Meet the test subjects

According to the chronology of creation and alphabet, it is most logical to start with MMCplus - a direct descendant of those good old MMC cards, with a capacity of ten or two megabytes, from which all branches of the family tree of both MMC and SD families began their "pedigree". But the rest, in fact, are lateral shoots, and MMCplus, I repeat once again, is direct, albeit in its content (and slightly in shape - the contact group is completely different) significantly different from the ancestor. However, we have seen a lot of cards of this standard, so I'll let you know that its real capacity, according to Everest, is 973 MB, and let's move on.

MMC cards were originally developed with an eye to maximum compactness, but time has shown that they are too large for some applications. A new shoot sprouted from the tree - RS-MMC cards, which looked like cut off to the length of MMC. Later, DV RS-MMC appeared on their basis, differing in support of supply voltage not only 3.3 V, but also 1.8 V, since power consumption is directly related to voltage, the need to reduce it in mobile devices is obvious. And after the appearance of the MMC 4.0 specifications, MMCmobile - DV RS-MMC was released with support for new operating modes. If you look from the other side, you can call these cards and RS-MMCplus, fortunately, for full-size models it is also recommended (albeit optional) to support 1.8 V. At first, all RS-modifications were noticeably inferior in capacity to the base ones (for purely technical reasons ), however, as technology develops, prices for high-density flash microcircuits decrease and users' appetite grows (mobile phones, where such cards are in use, have long been competing with digital players with considerable success and are getting closer and closer to the domain of digital cameras), a gap in the case of mass modifications were increasingly reduced. However, I have not yet seen the announcement of an 8 GB MMCmobile, and MMCplus has no problems, but in a retail network (at least in Moscow), both cards are still limited to 2 GB. As I said, we are testing a card with a capacity of 1 GB declared or (according to Everest) 988 MB real.

The Secure Digital standard originated from MMC a long time ago, and is not its direct descendant - the cards are similar, but, strictly speaking, they do not have to be compatible in any direction (however, thanks to the manufacturers of consumer equipment, we can often use both, but this is achieved using dual-standard controllers). Nominally, two versions of the specifications were replaced (and they existed different time), but, as I wrote at the beginning of the article, version 1.1 will not disappear anywhere in the near future, and it will never go anywhere from cards up to 2 GB. We are testing just a gigabyte card, and not a simple one, but an "extreme" one. However, the speed limit from the point of view of Kingston is at 133x, and some manufacturers have mastered even 150x, but the latter can mean anything in practice, and the promised 20 MB / s at least for read operations is now quite real. How real they are in our case - tests will show. I will only say that an attempt to achieve technical perfection and create universal cards for all applications played a bad joke with Secure Digital: virtually no one uses this very secure, but it eats the capacity of the card. According to Everest, Kingston's gigabyte SD card is only 941MB in size.

The use of flash cards in small-sized technology, as I said, led to the flourishing of their smaller modifications. If the MMC-alliance focused on RS-MMC / MMCmobile, then miniSD cards were an alternative from the SD-association. It should be noted that the position of the Alliance is slightly better - in the case of MMC cards are physically and electrically compatible in terms of the slot. The SD Association did not cut it off, but came up with a new form factor compatible with the "ancestor" only with the help of special adapters. And so the features are the same - reduced size and reduced supply voltage. The capacity has been reduced for a long time, but now both SD and miniSD are equally constrained by the standard, that is, 2 gigabytes (in practice, nevertheless, there is a difference - "non-standard" cards with twice the capacity in the case of SD exist, but nobody can make such miniSDs did not dare). By the way - the real capacity, which is the funny thing, in our case is larger for miniSD: 949 MB according to Everest :)

And now we will measure your boy- used to say the hero of one cult cartoon. The cards, of course, are not boys (and not girls :)), and I am not Pechkin, the postman, but without measurements, in our time, too, nowhere.

Testing methodology

Testing was carried out on a computer with the following configuration:

• EpoX 8NPA SLI
• AMD Athlon 64 3200+ (512K L2)
• 1 GB PC3200 DDR SDRAM
• system hard drive Western Digital WD740GD
• Apacer MegaSteno AM230 card reader
• Windows XP Pro + SP2

To measure the parameters of the subjects, the Lavalys Everest software was used. Ultimate Edition 2006 2.80, or rather, a test of disk drives included in it.

Competitors

Since our cards are of different standards, the diagrams will show everything that we have previously tested on this card reader. At the same time, among other things, let us once again compare the capabilities of MMC 4.x and SD 1.1 with each other: yet we have not tested so many of them so far to deny ourselves the pleasure :)

Reading tests

Nobody managed to repeat the record of the ultra-fast MMCplus card from Apacer in this case. Kingston MMCplus, judging by the results, supports only four data lines and the mandatory (from the point of view of the standard) clock frequency of 26 MHz. MMCmobile is noticeably faster (most likely due to the utilization of the entire possible bus width), but it falls short of high-speed SD cards. On the other hand, both SD and miniSD cards with a speed of 133x reach the results, despite the fact that no one announced a record speed for the latter.

The access time for reading for most cards has long been within the range of 0.5-1.5 ms. Our today's test subjects were no exception. As a funny grimace of fate, one can regard the fact that their results are arranged in alphabetical order, despite the alternation of formats in it :)

Write tests

miniSD lags far behind the full-sized card, although it works quite quickly. SD showed exactly the same result as 133x from Pretec - sometimes, it turns out, you can pay attention to Xs. In the MMCplus / MMCmobile pair, the positions have changed: judging by the speed, the second card uses MLC chips with all that it implies. And in the first, the read and write speeds do not differ, which works in favor of the theory of the narrowness of the data bus - the flash microcircuits themselves would have "gotten" more, but they are not given them.

With one exception, write access times are as expected. However, an exception deserves a separate mention: the write access time for SD Ultimate is lower than for the fastest hard drives, although the opposite picture is observed for most flash drives (as you can see in the diagram). This result is not unique - the Pretec i-Disk Diamond flash drive also responds quickly. At this rate, all flash drives will soon overtake their magnetic counterparts in all performance parameters;) Still, the problem with a limited number of rewriting cycles should be solved, the price should be reduced, and that's it - solid-state drives will play a death march to their competitors :)

Real capacity

Above (in the description of the cards) I indicated it, but for convenience of comparison I will repeat it in the table:

What conclusions can be drawn? Firstly, you shouldn't count on the declared capacity - the real one is much less. Secondly, even within the framework of the products of one company of the same standard, it can differ markedly. Thirdly, what I paid attention to, the capacity of MMC cards, all other things being equal, is higher than that of SD: nothing is given for nothing in this world. The difference between the minimum and maximum in today's testing reaches 47 MB ​​- quite recently cards with a lower total capacity were quite a mass product (smaller ones still often invest in a set of cameras);)

Prices

The table below shows the average retail prices of cards tested today in Moscow, relevant at the time you read this article:

Total

Not too long ago, we became convinced that MMC cards can be much faster than SD cards. Today we have seen not the first confirmation that they are not always faster, even under ideal conditions. In the old equipment, everything will be even worse for MMC - high-speed SD cards can lose two times in speed, while high-speed MMCs can "sink" by more than an order of magnitude.

As for the actual Kingston cards, they all demonstrate very decent speed indicators, even when they were not promised (when they promised, the reality corresponds to the promises). At the same time, they are distinguished by a democratic price, which, coupled with the popularity of this brand and a good warranty period, makes them a very reasonable candidate for purchase. Everything. And which ones - depends on your preferences (or rather, the preferences of your digital equipment) in terms of tires and form factors.

Various memory cards are typical examples of external flash drives. Today, many of the devices in our use, such as: cell phones, cameras, media and MP3 players and others, use memory cards as information carriers.
We believe that it will not be superfluous to know the features that various types of memory cards have, each of which is designed for a specific device.

What's inside these cards ...

Flash memory is a type of data storage, the main purpose of which is to increase functionality modern mobile devices. This allows manufacturers to lead the market and produce equipment demanded by users. A huge advantage of memory cards is the absence of additional power requirements, they are content with what is already in the device where they are used. Kara memory is easily filled with information and just as easily released from it. There are no mechanical moving parts in it, therefore it requires a minimum of power and its life is practically unlimited. Memory cards allow you to rewrite information from tens of thousands of cycles to a million.

The storage period of data on these devices is quite long and ranges from 20 to 100 years. Another plus is its low sensitivity to external influences, vibrations and shocks.

But one of the biggest advantages of memory cards is their compactness. With a thickness of three millimeters or less, the card has a maximum length of only four centimeters.

Variety of varieties

In the documentation for your device, there is always a description or abbreviation of the type of memory cards that this device can use. Having decided on the type of card, choose a manufacturer, focusing on the most famous and already proven manufacturers. Some of them have memory cards equipped with various adapters that significantly increase functionality and allow the memory card to be used in other devices.

Today there are seven main types of memory cards.
CompactFlash, otherwise CF, consisting of two types - CF type I and CF type II. These types of memory cards are the most common because of their characteristics, which sharply distinguish them from other types of compact storage media. Possessing a high speed of data exchange and providing a fairly high amount of memory, these cards have, in aggregate, a very low price in relation to megabytes / ruble, which is very attractive for those who produce mobile devices, that and for those who use them. According to all available data, it is currently the most common type of memory card.

IBM Microdrive- another type of memory cards for which the format does not quite fit this definition Compact Flash type II due to the fact that it is practically a reduced copy of the hard drive. Having a cost much lower than other types of memory cards, but it is a less reliable device due to moving parts. Another negative aspect of this card is its higher power consumption. Therefore, rare manufacturers use this variety in their products, the connectors of which correspond to CF type II.

SmartMedia- is also a representative of inexpensive and compact flash cards (only up to one millimeter thick). The low cost of these cards is determined primarily by the use of available components, but this, in turn, is also a disadvantage, since the use of inexpensive components can lead to abnormal cases and can cause loss of information.

Multimedia Card (MMC)- This is perhaps one of the best representatives memory cards of this class, the main advantages of this type of memory cards are small size and low power consumption. True, all this affects the speed of information exchange. The dimensions of these cards are 24x32x1.4 mm, and the short one is 24x18x1.4 mm. They are used mainly in cell phones and other devices, which are very compact in size.

SecureDigital (SD)- With their dimensions these memory cards are slightly inferior to MMC, but they are more preferable from the point of view of the speed of information exchange when working with a large size of the stored data. This feature dictates higher prices for them.

MicroSD- practically in terms of its characteristics it is not inferior to SD, while having a smaller size. Almost all memory cards of this type come with SD /

SD and MMC are backward compatible, so MMC memory cards can be installed and operated instead of SD, but the reverse is alas - impossible. Moreover, in latest versions devices manufactured by manufacturers (phones, players) only install an SD-type connector to introduce the versatility of the card (it is even indicated in the documentation as an SD / MMC connector).

MemoryStick- specially made and used practically only in devices manufactured by Sony. The dimensions of this memory card are 24 * 32 / 1.4 (2.1) mm. The card is very protected from tampering, and its performance is very similar to a SecureDigital (SD) memory card. However, its weak point is the small amount of stored information.

According to the latest statistics, currently the most common, generally accepted and used are memory cards of types CompactFlash and SD / MMC.

For ease of evaluation appearance and dimensions of various types of cards, we will show them clearly:

1 = MMC Plus (Multimedia Card)
2 = SD Mini (Secure Digital)
3 = SD Micro (Secure Digital)
4 = MMC Mobil (Multimedia Card)
5 = MS Pro (Memory Stick Pro)
6 = MS Pro Duo (Memory Stick Pro Duo)
7 = RS MMC (Multimedia Card)
8 = SM (Smart Media)
9 = CF (Compact Flash)
10 = SD (Secure Digital)

What should you choose after all? ...

As a rule, this task is one of the easiest, you just need to know what type of memory cards can be used in the device you purchased. You can easily find out from the documentation for your device or from the inscriptions on the case. The only thing that you personally can do is choose a manufacturer based on your preferences.

What volume...?

In general, the question is trivial. You can count by the number of photos, music or video time, but as a rule, whatever you choose, it always becomes small.

The most important thing is to decide how much you are willing to spend on it; for most, the choice decreases several times at once. Indeed, with a large amount of stored information, a high rate of exchange, minimal dimensions, the price may be too high for you to be able to afford it. So just choose the largest amount you can afford.

Multimedia Card (MMC) - portable flash memory card used in digital cameras, mobile phones etc.

MultiMedia Cards were developed in 1997 by SanDisk and Siemens based on Toshiba NAND memory, have a seven-pin connector (designed to minimize the risk of contact damage), the card consists of a plastic shell and a printed circuit board on which the memory chip is located. microcontroller and contacts. Despite the sequential nature of MMC, data and commands can be transmitted simultaneously. The MultiMedia Card operates at 2.0V-3.6V, but there are also versions with lower power requirements. The SD Card has a nine-pin interface, developed jointly by Matsushita, SanDisk and Toshiba in 2000.

There is also a Micro Memory Card (MMC), which is structurally identical to the Multimedia Card, but differs in logical layout and is intended exclusively for use in SIMATIC S7 programmable logic controllers from Siemens AG.

Dimensions 24 × 32 × 1.5 mm.

Since 2004 it is also available in a reduced case 24 × 18 × 1.5 mm

end of form start of form With a simple mechanical adapter, RS-MMC cards can be used with equipment designed for "full-size" MMC. Dual Voltage Reduced Size MMC (MMCmobile) are also available, which can operate not only at a standard supply voltage of 3 V, but also at 1.8 V.

MMC is mostly compatible with the later developed SD card and can be used instead of SD. In the opposite direction, replacement is most often impossible, since SD cards are thicker than MMC and simply mechanically cannot fit into the MMC card slot.

MMC uses a relatively simple open data transfer protocol, therefore, unlike Secure Digital (SD), it can be used in DIY devices.

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