History and evolution of memory cards

A memory card is an electronic data storage device used for storing digital information, typically using flash memory. Read about the history and evolution of memory cards, their advantages and disadvantages, and the future of flash memory in this blog post.

What is flash memory and where is it used?

Flash memory is a compact, widely used electronic storage medium, that can be electrically erased and reprogrammed. It can store data for long periods of time without being connected to a power supply (its memory is non-volatile, unlike RAM). There are two types of flash memory, using the same basic technology with slightly different ways of reading and writing data – NAND and NOR flash memory.

Flash memory cards are commonly used in portable electronic devices, such as digital cameras, mobile phones, laptops, computers, tablets, PDAs, portable media players, video game consoles, etc. Basically, it is hard to go a day without using at least one device that uses a flash memory card nowadays.

Memory card classes and speeds

The read speed of your memory card determines how quickly data can be transferred from your card. A slower speed means it will take longer to upload photographs to your computer. 

Memory Card details

Card Speed: Class 4, Class 6, Class 10, UHS-1 and UHS-3

Each SD or Micro SD card has a speed rating, called class. The larger class number corresponds to a faster level of writing/recording speed allowing the card to store at a higher speed.

The Class reading system corresponds to the minimum read/write speed in MB/s as below

•         Class 2 - 2MB/s

•         Class 4 - 4MB/s

•         Class 6 - 6MB/s

After the Class 10 classification, it becomes more complicated. An additional standard called UHS was introduced, which allows cards to reach higher speeds. Here we see a similar system – UHS Class 1 (or just U1 or U-I), which has a minimum performance rating of 10MB/s writing speed, while UHS Class 3 (or U3 / UHS-III) has a rating of 30MB/s. UHS Class 3/III supports 4K video recording. UHS speed classes are shown on the card with a number inside a U.

Confusingly, UHS Class 1 and Class 10 refer to the same 10MB/s speed, so sometimes you’ll see cards that are labeled both as Class 10 and UHS-1.