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Secure Digital, officially abbreviated as SD, is a
proprietary {{Short pages monitor logical sectors (smaller than 7.8 GB):
FAT32 File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons b ...
with partition type 0Bh and EBPB 7.1 ** Capacity of at least 16,450,560 logical sectors (larger than 7.8 GB):
FAT32 File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons b ...
with partition type 0Ch and EBPB 7.1 * For SDXC cards: exFAT with partition type 07h Most consumer products that take an SD card expect that it is partitioned and formatted in this way. Universal support for FAT12, FAT16, FAT16B, and FAT32 allows the use of SDSC and SDHC cards on most host computers with a compatible SD reader, to present the user with the familiar method of named files in a hierarchical directory tree. On such SD cards, standard utility programs such as Mac OS X's "" 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, 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. 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 Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use ...
; newer technology to increase the storage capacity of a card provides worse write endurance. When reformatting an SD card with a capacity of at least 32 MB (65,536 logical sectors or more), but not more than 2 GB, FAT16B with partition type 06h and EBPB 4.1 is recommended if the card is for a consumer device. (FAT16B is also an option for 4 GB cards, but it requires the use of 64 KB clusters, which are not widely supported.) FAT16B does not support cards above 4 GB at all. The SDXC specification mandates the use of
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washi ...
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