Solid State Storage

Solid-state removable devices don’t contain any moving parts, making them highly reliable and robust. Instead, they use a form of random access memory (RAM), similar to that found inside your computer. Unfortunately, this kind of storage is always much more expensive than traditional disk-based technology.

Several varieties of RAM card are used in digital cameras, personal organisers and MP3 players. The amount of information stored on a card is dependent on its capacity and the kind of content. For example, the card in a camera can store numerous low-resolution pictures or a few of high resolution. Typically, a 10 MB card accommodates five high-quality images, although dozens can be stored if compression is used, usually compromising the quality.

Although various types of card are available, they nearly all contain flash RAM. The most common varieties are CompactFlash card, SmartMedia card, MultiMedia Card (MMC), Memory Stick Duo, Memory Stick Pro, Secure Digital Multimedia card (SD/M) and PC Card, the last of which can be plugged directly into many portable machines.

  Card Types

The following types of media can be encountered:-

CompactFlash (CF) Card

This thin silver-coloured card, approximately one-inch square, is used in three times as many products as the SmartMedia card, including numerous digital cameras and some personal organisers, such as the original Psion Series 3. Common card sizes include 2, 4, 8, 16, 24, 32, 48, 64, 96, 128, 192, 256, 320 and 512 MB, as well as 1, 2, 4, 8 and 12 GB, although the final capacity is reduced by formatting. These cards also have an onboard controller to ‘map out’ any faulty areas of RAM.

Cards can be read using a CompactFlash card reader, which is usually connected to your machine via USB: some readers of this kind also accept other types of memory card. Alternatively, you can get a CompactFlash to PCMCIA adaptor and plug it into the PC Card slot in a portable machine.

Memory Stick Pro

The original proprietary format from Sony, commonly used in their portable computers, digital cameras and MP3 players. Sizes include 8, 16, 32, 64, and 128 MB, as well as others up to 4 GB.

Memory Stick Duo

A smaller version of the above Memory Stick, as used in more recent consumer products. Such cards can also be used in ‘Pro’ devices by employing a Memory Stick Duo Adaptor. Sizes range from 16 MB up to 2 GB.

MultiMedia Card (MMC)

This card, found in newer Palm organisers, cameras, video cameras (for still images) and portable MP3 players, is smaller than the older CompactFlash or SmartMedia devices and is available in capacities of 8, 16, 32, 64 MB and up to 4 GB. The Secure Digital Multimedia (SD/M) card (see below) is physically identical, with many devices, such as Palm organisers and some card adaptors, accepting both types. However, some equipment only works with one type of card.

Reduced Size MultiMedia Card (RS-MMC)

This small form of MMC is about the size of a postage stamp and is used in a wide range of devices. An adaptor can be used to engage this kind of card into a standard MMC or SD slot.

MMCmicro

The smallest version of MMC, often used in mobile phones. An adaptor can be used to engage this kind of card into a standard MMC or SD slot. Sizes range from 16 MB to 1 GB.

PC Card (PCMCIA Card)

This card, defined by the Personal Computer Memory Card International Organisation (PCMCIA), comes in Type I, Type II and Type III versions, although the Type I variety is more common. Capacities include 4, 5, 8, 10, 16 and up to 128 MB and to 16 GB

To read a PC Card you may need a PC Card reader that connects to your computer via USB: some readers of this kind also accept other types of memory card. Alternatively, insert the card into the PC Card slot of a suitable portable computer.

Secure Digital Multimedia (SD/M)

This kind of card is physically identical to a MultiMedia Card (MMC) but incorporates an encryption feature that can prevent the copying of MP3 music files or electronic books (e-books). SD/M cards can often be used in MMC slots and vice versa, although some equipment only accepts one type of card. Typical capacities include 16, 32, 64, 128, 256 and 512 MB, as well as 1, 2 and 4 GB.

Mini Secure Digital (MiniSD)

This smaller version of the SD/M format is about the size of a postage stamp and often has a capacity of 256 MB. An adaptor can be used to engage this kind of card into a standard SD slot. Sizes range from 16 MB to 2 GB.

Micro Secure Digital (MicroSD)

The smallest version of the SD/M format, this is about half the size of a postage stamp. Sizes range from 16 MB to 1 GB.

SmartMedia (SM) Card

This wafer-thick black oblong card is cheaper and flimsier than CompactFlash. Sizes include 2, 4, 8, 16, 32, 64, 128, 256 and 512 MB. Incompatible 5 volt (V) and 3.3 V versions can be encountered.

To read an SM card you’ll need a SmartMedia card reader that connects to your computer via USB: some readers of this kind also accept other types of memory card. Alternatively, you can use a SmartMedia to PCMCIA adaptor in the PC Card slot of a suitable portable computer.

Solid State Disk (SSD)

This special card is used in the Psion Series 5 personal organiser.

USB Flash Drive

Although described as a ‘drive’, this is actually an enlarged USB plug containing a solid state memory. You simply plug it into a spare USB port on your computer and it appears on the desktop as a normal drive. Best of all, it doesn’t require any special software on a Mac OS X computer. Standard sizes include 32, 64, 128, 256 and 512 MB, as well as 1 GB.

xD-Picture Card

A newer and very small flash memory format introduced by Fuji and Olympus, providing a read speed of 5 MB/s and a record speed of 1.3 to 3 MB/s. At the time of writing, sizes include 16, 32, 64, 128, 256, 512 MB and 1 GB. The format is designed to accommodate up to 8 GB in the future.

To read a Picture Card you’ll need a Picture Card adaptor of an appropriate type that can be plugged into either a PC Card slot or a CompactFlash card slot.

©Ray White 2006.