The microSD card has helped propel the smartphone market by giving both manufacturers and consumers greater flexibility and freedom. SD Standards Brochure 2017" (PDF). Archived from the original (PDF) on 2017-03-30 . Retrieved 2017-03-29. SDXC adopts exFAT one of the Windows file systems as a mandatory feature to handle large data volumes and file sizes over 4GB. Short for Secure Digital High Capacity, SDHC is a type of flash memory card based on the SDA (SD Association) 2.00 specification which enables SD cards to reach a higher capacity up to 32GB. Ng, Jansen (2009-12-22). "Toshiba Sampling First SDXC Flash Memory Cards". DailyTech. Archived from the original on 2010-11-25 . Retrieved 2009-12-22.

While it's generally safe to assume that a higher Speed Class correlates to faster all-around performance, and UHS cards faster still, some manufacturers also quote a maximum speed for their products.

Memory cards

Most SD cards ship preformatted with one or more MBR partitions, where the first or only partition contains a file system. This lets them operate like the hard disk of a personal computer. Per the SD card specification, an SD card is formatted with MBR and the following file system:

All SD card families initially use a 3.3 volt electrical interface. On command, SDHC and SDXC cards can switch to 1.8V operation. [84] The standard was introduced in August 1999 by SanDisk, Panasonic (Matsushita) and Toshiba as an improvement on MultiMediaCards (MMCs). [1] SDs have become an industry standard. The three companies formed SD-3C, LLC, a company that licenses and enforces intellectual property (IP) rights associated with SD memory cards and SD host-and-ancillary products. [2]In 2008, the SDA specified Embedded SD, "leverag[ing] well-known SD standards" to enable non-removable SD-style devices on printed circuit boards. [153] However this standard was not adopted by the market while the MMC standard became the de facto standard for embedded systems. SanDisk provides such embedded memory components under the iNAND brand. [154]

However, depending on the card’s manufacturer, you may not be able to figure out the speed class of your card. In this situation, it is recommended to use the Disk Benchmark feature of MiniTool Partition Wizard to test the disk speed. On such SD cards, standard utility programs such as Mac OS X's " Disk Utility" or Windows' SCANDISK can be used to repair a corrupted filing system and sometimes recover deleted files. Defragmentation tools for FAT file systems may be used on such cards. The resulting consolidation of files may provide a marginal improvement in the time required to read or write the file, [159] but not an improvement comparable to defragmentation of hard drives, where storing a file in multiple fragments requires additional physical, and relatively slow, movement of a drive head. [ citation needed] Moreover, defragmentation performs writes to the SD card that count against the card's rated lifespan. The write endurance of the physical memory is discussed in the article on flash memory; newer technology to increase the storage capacity of a card provides worse write endurance. [ citation needed] Since late 2009, newer Apple computers with installed SD card readers have been able to boot in macOS from SD storage devices, when properly formatted to Mac OS Extended file format and the default partition table set to GUID Partition Table. [151] (See Other file systems below).Version 3.01 also introduced the Ultra High Speed (UHS) bus for both SDHC and SDXC cards, with interface speeds from 50MB/s to 104MB/s for four-bit UHS-I bus. [54] (this number has since been exceeded with SanDisk proprietary technology for 170MB/s read, which is not proprietary anymore, as Lexar has the 1066x running at 160MB/s read and 120MB/s write via UHS1, and Kingston also has their Canvas Go! Plus, also running at 170MB/s). [55] [56] [57] [58] Although SDHC and SDCX belong to SD cards, there are some differences between these two cards. Let’s explore the differences between them in some aspects. SDUC Host Devices can use SD memory cards, SDHC memory cards, SDXC memory cards and SDUC memory cards.

NOTE: If the card reader uses the DDR208 controller on the UHS 1 pins, the card reader will perform at 180 MB/s on applicable UHS 1 cardsMicro SDHC cards come in the standard size of 11mm by 15mm. What are the advantages of a micro SDHC card?