Specifications

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As flash media grew in popularity, they found more uses in other devices. MP3 audio players and
tiny voice recorders use the smaller flash memory cards as replacements for bulky and unreliable
tape cartridges. Printers have added slots for accepting flash media containing digital image files
straight from digital cameras or large graphic files transferred from computers. PDA’s (personal
digital assistants) added flash memory slots for transferring files to or from personal computers.
Flash media have even replaced logging tapes in military aircraft and railroad locomotives.
The choice of flash memory depends on each one’s special design features. Compact Flash’s
thicker profile allows greater memory storage, and its early introduction has allowed it to be widely
used in many devices. The smaller size of Secure Digital cards, on the other hand, has been an
advantage in hand-held devices such as portable MP3 players and lightweight digital camcorders.
New devices such as the Memorex ThumbDrive incorporate flash memory in a lightweight,
portable package that plugs directly into USB ports for easy file transfers. Figure 15 is a profile of
the different types of cards showing their relative dimensions. Figure 16 is a chart comparing
features of each of the different flash memory cards and the most common type of devices that
use each type.
FLASH CARD SPEEDS
Flash cards, like optical media, seem to concentrate on speed of data transfers in addition to
capacity as distinguishing features of the card. Data transfer speeds are determined by a number
of variables, however, and there are no common standards that appear to be used uniformly in
specifying rates of speed. A speed of “1X” is 150 kilobytes per second. Faster speeds are
multiples of that 1X: 4X = 600 kB/s; 12X = 1.8 MB/s; 32X = 4.8 MB/s; and 40X = 6 MB/s. Read
CompactFlash SmartMedia MMC SD Memory Stick xD Picture
Card
Mi niSD
MMCmicro microSD
Memory Stick Duo
RS-MMC/
MMCmobile
M2
Figure 15
Flash Card Profiles