The application speed class that the memory card corresponds to.
When working with applications that use a memory card (for example, mobile games), information is written and read not in a continuous stream, as when recording video or copying data, but in separate small fragments, moreover, from random sections in the memory of the drive (the so-called random write / read). So a high video recording class (see above) does not always mean good performance when working with demanding games and other resource-intensive programs. Therefore, in the characteristics of memory cards, they began to separately indicate the speed class for applications.
The key indicator for assigning one or another class is the minimum number of IOPS (input / output operations per second) that the media can provide in random write and read mode. The following classes are relevant today:
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A1 — at least 1500 IOPS for reading and 500 IOPS for writing;
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A2 — at least 4000 IOPS and 2000 IOPS, respectively.
The speed of continuous recording (for example, when shooting video) in both cases must be at least 10 MB / s (often it turns out to be even more — see “Speed class”, “Video recording class”).
In the future, we can expect the appearance of new, more performant classes for applications. Also note that this parameter significantly affects the price of the card.
Factor describing the maximum speed of the card in read mode. In this case, 150 KB / s is taken as a unit; thus, for example, a speed value of 533x corresponds to 150 * 533=79,950 KB / s, that is, about 80 MB / s.
In general, this parameter is quite specific; in fact, it is easier to focus on the directly claimed reading speed (see below). However, sometimes it is not indicated — in such cases, the speed value will be primarily useful.
