(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
One can find MicroSD cards, smaller variants of the SD (Secure Digital) cards in certain cell phones, personal digital assistants, and other smaller, lighter devices. One can read MicroSD cards with 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 cards, the oldest and most commonly used storage media. They have a max capacity of 2GB.
How do SDHC and SD Cards differ? In terms of size and shape, SDHC cards are the same size and shape as SD cards but conform to the new SD 2.0 specifications An SD card 4GB or above we classify as an SDHC card. Currently, SDHC specifications allow for memory cards of a capacity between 4GB and 32GB.