How Pictures Are Stored on a Chip
Compact Flash Types I and II
About the size of a book of matches, Compact Flash cards were developed by SanDisk in- In addition to memory chips for storing data, the circuit boards of CF cards contain
controller chips to manage the flow of that data into the card. Manufacturers constantly
tweak the chip to beat their competitors in the race to save photos, an important factor when
shooting bursts of exposures. Although larger than many other types of memory cards,
Compact Flash is valued by professional photographers for the capacious storage. CF Type I
stores as much as 6GB; Type II Compact Flash, which is nearly twice as thick as Type I,
holds up to 12GB.
xD-Picture Card
Although it’s only about the size of a postage stamp, the xD (eXtreme Digital) Picture Card
holds up to 8GB of data. It has no controller chip built into it and works only with cameras
that have their own controllers for managing transfers to the memory card. The card is used
for the most part only by Fuji and Olympus cameras.SD Card
The SD (Secure Digital) Card was developed to comply with the copy protection devised by
the Secure Digital Music Initiative. But once that protection was cracked, the SD aspect of
the card became moot. The dime-sized card has taken the largest market share for digital
cameras because of its relatively low cost and capacity to store up to 4GB, expected to rise
to 8GB. The SD Card is unique in having a tab on one edge that can be moved to a write-
protect that prevents erasure of the card’s contents.Sony Memory Stick
Sony introduced the Memory Stick in 1999 as the only memory card that works with most of
Sony’s products. Roughly the same dimensions as a stick of gum, the Memory Stick has been
replaced largely by a Pro version that holds up to 4GB of data, compared to the original
stick’s 128MB. Its greatest advantage is that data on a Memory Stick can be used with a
variety of Sony products that have built-in readers. Photos recorded to a Memory Stick, for
example, may be displayed on many Sony televisions.Whatever format you choose for saving your photos, the first stopping place will be some sort of flash memory. Flash memory comes in
the form of thin cards, fat cards, chewing gum-size sticks, and even key chains. Increasingly, flash memory makers are developing faster
methods of getting data from a camera into the memory to keep pace with cameras that take multiple shots in a few seconds. The faster
memory cards move data more than 100 times as fast as the slowest. What they all have in common is that they do not lose whatever is
stored in them simply because someone turns off the camera.(^114) PART 2 HOW DIGITAL CAMERAS CAPTURE IMAGES
Smart Media
Smart Media (SM) cards today are rarely used with any devices post-2001. They have no
controller built into them, so they will work only with hosts that have the appropriate controller.
SM cards hold a maximum of 128MB, which lags far behind the gigabytes of storage other
media hold.
How Fast Is X-Rated Memory?
Most flash memory cards use an X rating to indicate how quickly they store data
from a camera. The X refers to the speed of the first flash cards, which moved
150KB a second. A card that bills itself as 80X is claiming to transfer
12,000KB/s.