(Secure Digital Memory Card) A family of compatible and very popular flash memory cards used primarily for storage in cameras and phones. Introduced in 1999 by Panasonic, Toshiba and SanDisk as the successor to the MultiMediaCard (see MMC), the SD technology is managed by the SD Association (www.sdcard.org).
Capacities reached 512GB for the full-size card and 1TB for the tiny microSD. For video recording, SD cards support various write speeds (see SD card classes), and although SD cards were designed for copyright protection (the “Secure” in SD), they were never much used for that purpose (see CPRM). SD uses NAND flash technology (see flash memory). See Video HD, Eye-Fi and SDIO card.
SD Express – More Speed
In 2018, SD Express was introduced, which supports additional interfaces and higher speeds while keeping backward compatibility with the billions of SD hosts in the world. See SD Express.
Year Maximum File Format Into Capacity System SD 1999 2GB FAT16 SDHC 2006 32GB FAT32 SDXC 2009 2TB exFAT SDUC 2018 128TB exFAT
MicroSD is a smaller variant of the SD (Secure Digital) card and is used in certain cell phones, PDAs, and smaller, lighter devices. MicroSD cards can be read by regular SD card slots through an adaptor.
|Capacity||Up to 128GB||Up to 2GB|
|Compatibility||SD smaller devices such as a cell phone||Compatible only with SD host devices|
|Types||micro SD||Standard SD, mini SD and micro SD|
|Speed||Slower as compared to SDHC||Slower as compared to SDHC|
SD (secure digital) cards are the oldest, least used, and limited to 2GB of storage. SDHC (high capacity) cards can store up to 32 GB of data, while SDXC (extended capacity) cards can store up to 2 terabytes (2000 GB).
What is the difference between SDHC and SD Cards? … SDHC is the same physical size and shape as standard SD but meets the new SD specification of version 2.0. If the SD card is 4GB or above, it is classed as an SDHC card. Currently, SDHC specifications allow for memory cards of a capacity between 4GB and 32GB.