read it via :
http://en.wikipedia.org/wiki/Secure_Digital_cardSecure Digital (SD) is a flash (non-volatile) memory card format developed by Matsushita, SanDisk and Toshiba for use in portable devices, including digital cameras, handheld computers, PDAs and GPS units. As of fall 2007, SD card capacities include 8 MB, 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, and 512 MB, 1 GB, 2 GB, 4 GB, 6 GB, 8 GB, 16 GB. Several companies have announced SD cards with 32 GB. Cards with 4-32 GB are considered high-capacity. SDHC[1].
The format has proven to be very popular. However, compatibility issues between older devices and the newer 4 GB and larger cards and the SDHC format[2] have caused considerable confusion for consumers.
of which... please be careful of those SDHC cards hor.
SDHC
A 8 GB Class 6 SDHC Memory Card
A 8 GB Class 6 SDHC Memory Card
A new SD format, SDHC (Secure Digital High Capacity, SD 2.0), allows capacities in excess of 2 GB. SDHC uses the FAT32 file system which supports partition sizes greater than 2 GB[10]. It uses the same form factor as SD, but the SD 2.0 standard in SDHC uses a different memory addressing method (sector addressing vs byte addressing), thus theoretically reaching a maximum capacity of up to 2048GB. SDHC cards only work in SDHC compatible devices, but standard SD cards work in both SD and SDHC devices. The SDHC trademark is licensed to ensure compatibility.[11]
In August 2007 Toshiba announced that they would be launching a 32 GB SDHC card[12] and an 8 GB microSDHC card worldwide in January 2008[13]. Toshiba also announced a 16 GB version available in the last quarter of 2007[14].
A number of Key Features have been published[15] for each:
1.SDHC Memory Card (High Speed Type)[16] (1) Realizes maximum write speed of 6 MB per sec. (2) "Class 4” SD Speed Class, guaranteeing sustained data write at 4 MB/s. (3) Integrates highly secure CPRM copyright technology.
2. microSDHC Memory Card[17] (1) Realizes large 8 GB capacity in a microSDHC Card. It can store 139 hours of music at a bit rate of 128kbit/s. (2) "Class 4” SD Speed Class, guaranteeing sustained data write at 4 MB/s. (3) Integrates highly secure CPRM copyright technology.
SDHC cards have SD Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum sustained write speed on to empty SDHC cards:
* Class 2: 2 MB/s
* Class 4: 4 MB/s
* Class 6: 6 MB/s
you should get a SDHC reader to prevent IO errors. something like the below :
those multi 20-in-1 reader that does everything are a touch n go affair. some works, some dun.
that's all for SD cards. enjoy. and good shopping.
