SD and SDHC compatibility issues
The SDHC specification was completed in June 2006, but by that time, non-standard high-capacity (>2GB) SD cards (based on the older 1.x specification) were already on the market. The two types of storage-cards were not interchangeable, creating some confusion among customers. Fortunately, such cards were expensive and represented a very small portion of the SD-card market, giving vendors of consumer devices and storage-cards the time to adopt the SDHC SD2.0 standard.
SD and SDHC cards and devices have these compatibility issues :
- Devices that do not specifically support SDHC do not recognize SDHC memory cards. Some devices can support SDHC through a firmware upgrade.
- SDHC devices are backward compatible with SD memory cards.
- Some manufacturers have produced 4 GB SD cards that conform to neither the SD2.0/SDHC spec nor existing SD devices.
- File System: SD cards are typically formatted with the FAT16 file system, while SDHC cards are typically formatted as FAT32. However, both types of cards can support other general-purpose file systems, such as UFS2/ext2 or the proprietary exFAT for example.
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