Invented by SanDisk Corporation in 1994, CompactFlash cards can support 3.3V and 5V operation and can switch between the two, in contrast to other small-form factor flash memory cards that can operate only at one voltage. The card was designed based on the PCMCIA PC Card standard and can fit into a PCMCIA slot with an adapter. There are two types of CompactFlash cards to accommodate different capacities:
Type I cards are 42.8mm x 36.4mm x 3.3 mm thick
Type II cards are 42.8mm x 36.4mm x 5.5 mm thick.
Secure Digital Card (SD card)
SD cards are used in many small portable devices such as digital video camcorders, digital cameras, handheld computers, audio players and mobile phones. In use since 1999, SD Memory Cards are now available in capacities between 16 Megabytes and 1 Gigabyte, and still growing. An SD card typically measures 32 mm x 24 mm x 2.1 mm and weighs approximately 2grams.
After the success of the SD Card (Secure Digital Card), the miniSD Memory Card was developed to meet the demands of the mobile phone market. The MiniSD Card provides the same benefits as the SD Card, but is smaller than the original SD Card. MiniSD Cards are typically found in many newer mobile phones with features such as built-in digital cameras, downloading and games, basically the mobile phones where the miniSD can meet the requirements for increased data storage. MiniSD cards are 21.5 mm x 20 mm x 1.4 mm and generally provide 16MB to 256MB of storage.
Mainly used in mobile phones and other small handheld devices the MicroSD format is currently available in capacities up to 4GB, and it roughly 1/4th the size of the SD card at 15mm W 11mm W 0.7mm. The MicroSD card is also the smallest memory card available.
Card adapters can be purchased that enable backwards compatibility — this would allow MicroSD cards to work in SD and MiniSD slots, and also for MicroSD cards to work in SD card slots.
The MultiMediaCard (MMC) standard was introduced by SanDisk and Siemens in 1997. The card itself is 32 mm x 24 mm x 1.4mm and is often used in place of the SD card. Transfer speeds of a MMC is around 2.5MB/s and they can often be used in SD Card readers.
Sony Memory Sticks
Sony Memory Sticks are light, compact and designed for a wide variety of devices including digital cameras, recorders, and more. With the use of an adapter most Sony Memory Sticks can be used with almost all Memory Stick PRO compatible products.
Memory Stick Micro (M2): 15 mm x 12.5 mm x 1.2 mm
Memory Stick PRO: 50 mm x 21.5 mm x 2.8 mm. The Memory Stick PRO format has an an 8-bit parallel interface with theoretical transfer rates up to 480Mb/s. It is commonly used in high megapixel digital cameras and digital camcorders.
Memory Stick PRO DUO: 31 mm x 20 mm x 1.6 mm. The Memory Stick PRO Duo media is about one-third the volume and half the weight of standard-size media, but offers all the advanced functions of Memory Stick PRO media.
Introduced by Toshiba in 1995 the SmartMedia cards are now considered obsolete despite its popular usage for five years. SmartMedia cards are 45 mm x 37 mm x 0.76 mm and could be found in their peak times in 16MB, 32MB, and 128MB versions. Even as an obsolete card, it is still sought after by users of older devices which cannot use memory cards larger than 128MB.
Abbreviated as xD (Extreme Digital), the xD-Picture Card is a type of removable flash memory designed for use in digital cameras. The xD is ultra-compact with its size of 20mm x 25mm x 1.7mm. The xD-Picture Card was developed by Fuji film and Olympus and are used in many models of digital cameras made by Olympus and Fujifilm.