Features of Memory Cards for Digital Cameras Part 1

The main specifications when looking at memory cards for digital camera memory are its capacity, including the type of memory format, transfer speed and compatibility.

Capacity

There are two main types of memory formats in used for digital cameras - flash and hard drive.

Flash

Flash memory formats are based on NOR and NAND memory types which stores information in cells made from floating-gate transistors. Flash memory formats are able to achieve smaller sizes for the same capacity because of its lack of moving parts.

However flash memory has a limit number of write cycles. As more and more write-erase are performed on the memory, the storage begins to deteriorate and eventually the flash memory becomes corrupted.

To prevent the pre-mature wearing of flash memory, a technique known as wear levelling is used. Wear levelling enable flash memory cards usually contains a chip that helps to arrange data so that writes and erases are distributed evenly across the memory blocks. In this way to concentrated use of a few memory blocks are avoided.

Hard drive

The only memory card for digital cameras that utilises the hard drive memory format is the MicroDrive. Microdrive memory is essentially the same as the hard disk you will find in your PCs, with a spinning magnetic drive; except its highly miniaturised.

Although hard drive memory was able to sustain a higher memory capacity for a long time in the arena of memory cards, recent developments in flash memory technology have finally overtaken the hard drive in memory storage.

However, hard drive memory do not suffer from the wear out of memory blocks like flash memory. Although hard drive memory do deteriorate from mechanical wear, this is usually takes a much usage compared to flash memory.

Compared to flash memory, hard drives are also less likely to be corrupted during an abrupt power loss. Flash memory tends to be moving old data in the device around when writing with wear levelling algorithms.

In the event of an abrupt power loss, old data may be corrupted in flash memory. Hard drive memory, on the contrary, are modified in place.

Moreover, hard drive algorithms have had much more years of experimentation and testing than flash memory.

Continued to read more here Memory Cards for Digital Cameras 2