Edited by Rudraksh at 2016-05-27 20:49

Hello everyone,
Most of us would be using SD cards. There is a wide variety of SD Cards. So I explain you every type of SD card. Let's get started.


Secure Digital (SD) is a non-volatile memory card developed by the SD Card Association (SDA) in 1999 for use in portable devices. SDA was introduced in 1999 by SanDisk, and Toshiba, in order to compete with the Memory Stick, a product launched by Sony in 1998. It was derived from MultiMediaCard (MMC). It was introduced in order to standardize the memory cards. The headquaters of the SDA is in San Ramon, California, United States.

The Evolution of SD Cards -

The SDA announced the SD card at the 2000 Consumer Electronics Show. The SDA started with about 30 companies and today it consists of about 2000 companies that make SD Cards. The samples came in the first quarter of 2000. The capacity of cards were 32MB and 64MB.

The MiniSD was announced in March 2003 by SanDisk Corporation. The SDA adopted the MiniSD card due to its small form factor. In September 2006, SDA introduced 4GB MiniSDHC. It had the same dimensions and characteristics like the MiniSD Card, just that the storage capacity was increased.

The microSD, announced in 2005, were originally named TransFlash (abbreviated TF or T-Flash). TransFlash  and microSD cards are functionally identical to each other. SanDisk and Motorola concluded that current size of the memory cards (miniSD)  were too large for smartphones. During its release, the microSD was released along with SDHC  for higher storage capacity. It had a minimum read / write speed of 17.6 Mbit/s. The SDA approved the final microSD specification on July 13, 2005. Initially, the storage capacity of microSD card were 32, 64, and 128MB.


Types of microSD cards -

SDA divides the microSD cards on the basis of-

• Class
• Storage Capacity
  

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Division on the basis of Class -

SDA distinguishes the SD cards on the basis of their speed. Different SD cards possess different read/write speed. Different speeds are needed for different jobs. Like a person recording 4K video requires a SD card with a faster read/write speed, than a person capturing simple images.

The different speed Classes are 2, 4, 6, and 10. In addition to this, there are UHS-I and UHS-II. They give extra read / write speed, but are expensive than the others. They also require UHS host devices, to function properly. They are useful for real-time broadcasts and capturing large HD

Class	Minimum Writing Speed	Application
Class 2	2MB/s	SD Video Recording
Class 4	4MB/s	HD Recording including Full HD
Class 6	6MB/s	HD Recording including Full HD
Class 10	10MB/s	Full HD Video Recording
UHS Speed Class 1	10MB/s	Real Time Broadcasting
UHS Speed Class 2	30MB/s	4K Video files

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Division on the basis of Storage Capacity -

SD card can be divided into SDSC, SDHC, SDXC, and SDIO on the basis of their storage capacities.

SDSC :

The first generation of microSD is known as Secure Digital Standard Capacity. It was developed to improve the MultiMediaCards (MMC). It had a asymmetrical design to prevent is from being inserted upside down. It had a storage capacity of 1MB to 1GB. It supported FAT16 file system. The host devices supported older SD cards, but higher SD cards weren't supported.

SDHC :

Standard Capacity High Capacity was introduced in January 2006. It had similar form factor as the SDSC. The difference was in storage capacity. It had a storage capacity of upto 32GB. It supported FAT32 file system. As mentioned above the host devices supported older SD cards, but not the SDXC cards.


SDXC :

Standard Capacity eXtended Capacity was announced in January 2009 and defined in version 3.01 of the SD specification, supports cards upto 2TB, compared to 32GB for SDHC cards. It adopts Microsoft's exFAT file system. Though some of them come pre-formated to FAT32. Version 3.0 also introduced the Ultra-High Speed (UHS) bus for both SDHC and SDXC cards.


SDIO :

Secure Digital Input Output (SDIO) is an extension of the SD specification to cover I/O functions. They are only involved in the input and output of devices. They use the normal SD port of the devices. They can be used to support GPS receivers, modems, FM Radios, Bluetooth and so on. SDIO Cards support most of the memory commands of SD cards. The SDIO and SD interfaces are identical, both mechanically and electrically. The host devices may support other simple SD cards. However, the reverse is not true.

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Source - Google (Various)