SDHC (short for Secure Digital High Capacity) memory cards are the most popular form of external storage for cameras, camcorders, mobile phones, and a host of other electronic devices. An SDHC memory card can store high definition photos, video and audio, and can be easily transferred from one device to another.
The SDHC memory card extends the original SD specification, allowing for greater storage capacity beyond the 4 GB limit for SD cards. Although almost all newer devices will support SDHC cards without issue, keep in mind that many older devices built to the original SD specification will not support SDHC cards.
Check with your device manufacturer to see if there is a firmware update available that allows your device to use an SDHC memory card. Please note that any device that supports SDHC will also support older SD cards.
The SDHC memory card is available in sizes from 4GB to 32GB. It is available in three different sizes: SDHC, miniSDHC, and microSDHC. The mini and micro formats were created for use in smaller electronic devices, such as mobile phones. All sizes share the same capacity and minimum speed capabilities. SDHC cards use the FAT32 file system, which is the same as used in earlier versions of Windows.
An SD-size adapter can be used for miniSDHC and microSDHC cards so that they can be used in devices that only accept full-size SDHC cards. Often the adapter will be packaged with the card itself.
There are four speed classes available for the SDHC memory card: Class 2 allows a minimum transfer speed of 2 MB / s. This enables standard definition video recording. Class 4 has a minimum transfer speed of 4 MB / s, while Class 6 has a minimum transfer speed of 6 MB / s. These speeds are applicable for high definition video recording.
The fastest speed class, Class 10, has a minimum transfer rate of 10MB / s and allows simultaneous HD recording. Consult the instruction manual that came with your device to determine which speed class is appropriate for your device.
Some devices have an SDIO slot, which can support SD and SDHC cards, as well as small devices such as GPS navigators, Bluetooth devices, network adapters, modems, and a host of other possible devices.
The SD specification is based on an older memory card standard called MultiMediaCard or MMC. Some devices that use SD cards can also read MMC cards. SD cards were manufactured to compete with the proprietary Memory Stick standard created by Sony. The SD format was created by SanDisk, Matsushita, and Toshiba, and was first introduced in 1999.
The next generation of SD cards, SDXC, has recently been introduced. SDXC cards can handle up to 2TB of data, with transfer speeds of up to 100MB / s. Uses Microsoft’s exFAT file system for portable drives. The first SDXC cards have just started to appear on the market. Like SD and SDHC cards, SDXC cards may not be compatible with devices that only support the SDHC standard.