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Chapter 10. Flash and Removable Storage
1 to a 0. Once a flash cell is programmed (that is, changed to a 0), the only way it can be changed
back to a 1 is by erasing it. The problem with this is that, although you can program individual cells
or pages, you can only erase cells or pages on a block basis, and a block usually consists of
thousands of cells (512KB in most cases). The actual programming and erasing process coaxes
electrons into and out of the transistor’s floating gate by a process known as Fowler-Nordheim
The two major types of flash memory technology are called NOR (Not OR) and NAND (Not AND).
Both use the same basic transistor (cell) design, but they differ in how the cells are interconnected.
NOR flash works more like dynamic RAM (DRAM), providing high-speed random-access
capabilities with the ability to read or write data in single byte quantities. NOR flash is the type of
memory used for flash ROMs, such as those found in motherboards, cell phones, and most devices
that have updatable firmware.
On the other hand, NAND flash works more like a storage device, reading and writing data in pages
or blocks instead of individual bytes. NAND flash is used in devices that store file-oriented data,
such as SSDs, USB key or thumb drives, digital cameras and digital film media, music players, and
more. NAND flash is denser than NOR flash, storing more data in a given amount of die space and
costing less overall for a given amount of storage.
The speed, low power requirements, and compact size of recent flash memory and SSD devices have
made flash memory a perfect counterpart for portable devices such as laptop computers and digital
cameras, which often refer to flash memory devices as so-called “digital film.” Unlike real film,
digital film can be erased and reshot. Ultra-compact, USB flash memory drives have all but replaced
traditional floppy drives, Zip/SuperDisk drives, and even optical discs for transporting data between
Several types of flash memory devices have been popular, including the following:
• CompactFlash (CF)
• SmartMedia (SM)
• MultiMediaCard (MMC)
• SecureDigital (SD)
• Memory Stick
• ATA Flash
• xD-Picture Card
• Solid-state drive (SSD)
• USB flash devices
Some of these are available in different sizes (Type I/Type II). Table 10.1 shows the various types of
solid-state storage used in digital cameras and other devices, listed in order of introduction.
Table 10.1. Different Flash Memory Devices and Physical Sizes
SSDs and USB flash drives are not listed because they do not have a single standardized form factor.
SSDs, normally used as hard disk drive (HDD) replacements, come in different form factors,
including the same form factor as 1.8-inch, 2.5-inch, and 3.5-inch HDDs as well as adapter card–
based versions that plug into a slot in the motherboard.
CompactFlash was developed by SanDisk Corporation in 1994 and uses the ATA (AT Attachment)
architecture to emulate a disk drive; a CompactFlash device attached to a computer has a disk drive
letter just like your other drives. When CompactFlash was first being standardized, even full-sized
hard disks were rarely larger than 4GB, so the limitations of the ATA standard were considered
acceptable. However, CF cards manufactured after the original Revision 1.0 specification are
available in capacities up to 128GiB. While the current revision 6.0 works in [P]ATA mode, future
revisions are expected to implement SATA mode.
The original size was Type I (3.3mm thick); a newer Type II size (5mm thick) accommodates highercapacity devices. Both CompactFlash cards are 1.433-inch wide by 1.685-inch long, and adapters
allow them to be inserted into laptop computer PC Card slots. The CompactFlash Association
(www.compactflash.org) oversees development of the standard.
Ironically, SmartMedia (originally known as SSFDC for solid state floppy disk card) is the simplest
of any flash memory device; SmartMedia cards contain only flash memory on a card without control
circuits. This simplicity means that compatibility with different generations of SmartMedia cards can
require manufacturer upgrades of SmartMedia-using devices. Now defunct, the Solid State Floppy
Disk Forum originally oversaw development of the SmartMedia standard.
If you use a SmartMedia-based Olympus digital camera that has the panorama feature, be sure
to use Olympus-brand SmartMedia because other brands lack support for the panorama feature.
The MultiMediaCard (MMC) was codeveloped by SanDisk and Infineon Technologies AG (formerly
Siemens AG) in November 1997 for use with smart phones, MP3 players, digital cameras, and
camcorders. The MMC uses a simple 7-pin serial interface to devices and contains low-voltage flash
memory. The MultiMediaCard Association (www.mmca.org) was founded in 1998 to promote the
MMC standard and aid development of new products. In November 2002, MMCA announced the
development of the Reduced Size MultiMediaCard (RS-MMC), which reduces the size of the
standard MMC by about 40% and can be adapted for use with standard MMC devices. The first flash
memory cards in this form factor were introduced in early 2004 to support compact smartphones. In
2008, the MMCA merged with JEDEC (www.jedec.org), which is the global leader in developing
open standards for the microelectronics industry.
A SecureDigital (SD) storage device is about the same size as an MMC (many devices can use both
types of flash memory), but it’s a more sophisticated product. SD, which was codeveloped by
Toshiba, Matsushita Electric (Panasonic), and SanDisk in 1999, gets its name from two special
features. The first is encrypted storage of data for additional security, meeting current and future
Secure Digital Music Initiative (SDMI) standards for portable devices. The second is a mechanical
write-protection switch. The SD slot can also be used for adding memory to Palm PDAs. The SDIO
standard was created in January 2002 to enable SD slots to be used for small digital cameras and
other types of expansion with various brands of PDAs and other devices. The SD Card Association
(www.sdcard.org) was established in 2000 to promote the SD standard and aid the development of
new products. Note that some laptop computers have built-in SD slots.
Reduced-size versions of SD include MiniSD (introduced in 2003) and MicroSD (introduced in
2005). MiniSD and MicroSD are popular choices for smartphones and can be adapted to a standard
SD slot. MicroSD is compatible with the TransFlash standard for mobile phones.
The original SD standard allowed for memory card capacities of up to 2GB. To support higher
capacities the SDHC (High Capacity) standard was created in 2006. SDHC supports cards from 4GB
to 32GB in capacity. To increase capacity beyond 32GB, the SDXC (eXtended Capacity) format was
released in 2009. SDXC supports capacities of up to 2TB. Note that devices are backward
compatible, meaning that a device that supports SDXC also supports SDHC and standard SD cards.
A device that supports SDHC also accepts standard SD cards, but such a device does not support
SDXC cards. Devices that support only standard SD do not support either SDHC or SDXC cards.
Sony Memory Stick
Sony, which is heavily involved in both laptop computers and a variety of digital cameras and
camcorder products, has its own proprietary version of flash memory known as the Sony Memory
Stick. This device features an erase-protection switch, which prevents accidental erasure of your
photographs. Sony has also licensed Memory Stick technology to other companies, such as Lexar
Media and SanDisk.
Lexar introduced the enhanced Memory Stick Pro in 2003. Memory Stick Pro includes MagicGate
encryption technology, which enables digital rights management, and Lexar’s proprietary high-speed
memory controller. Memory Stick Pro is sometimes referred to as MagicGate Memory Stick.
The Memory Stick Pro Duo is a reduced-size, reduced-weight version of the standard Memory Stick
Pro. It can be adapted to devices designed for the Memory Stick Pro.
Sony later released “Mark 2” certified versions of the Memory Stick Pro in 2008. This certification
indicated that the cards were suitable for use with AVCHD (Advanced Video Coding High
Definition) recording devices. Sony also released a smaller Memory Stick Micro (also called M2)
format in 2006, which was designed to compete with microSD. In 2009 Sony announced the Memory
Stick XC (eXtended Capacity) format in order to compete with SDXC.
Because the Memory Stick formats are proprietary and only used in Sony devices, I recommend
avoiding them wherever possible. In order to avoid using expensive and hard to find proprietary
memory, make sure any device you purchase accepts industry standard memory such as SD.
Fortunately, Sony’s newer devices are including support for industry standard SD memory formats in
response to the negative backlash against its proprietary Memory Stick.
ATA Flash PC Card
Although the PC Card (PCMCIA) form factor has been used for everything from game adapters to
modems, SCSI (Small Computer Systems Interface) cards, network cards, and more, its original use
was computer memory, as the old PCMCIA (Personal Computer Memory Card International
Association) acronym indicated.
Unlike normal RAM modules, PC Card memory acts like a disk drive, using the PCMCIA ATA (AT
Attachment) standard. PC Cards come in three thicknesses (Type I is 3.3mm, Type II is 5mm, and
Type III is 10.5mm), but all are 3.3-inch long by 2.13-inch wide. Type I and Type II cards are used
for ATA-compliant flash memory and the newest ATA-compliant hard disks. Type III cards are used
for older ATA-compliant hard disks; a Type III slot also can be used as two Type II slots.
In July 2002, Olympus and Fujifilm, the major supporters of the SmartMedia flash memory standard
for digital cameras, announced the xD-Picture Card as a much smaller, more durable replacement for
SmartMedia. In addition to being about one-third the size of SmartMedia—making it the smallest
flash memory format yet—xD-Picture Card media has a faster controller to enable faster image
Both 16MB and 32MB cards (commonly packaged with cameras) record data at speeds of 1.3MBps,
whereas 64MB and larger cards record data at 3MBps. The read speed for all sizes is 5MBps. The
media is manufactured for Olympus and Fujifilm by Toshiba, and because xD-Picture media is
optimized for the differences in the cameras (Olympus’s media supports the panorama mode found in
some Olympus xD-Picture cameras, for example), you should buy media that’s the same brand as your
Just as with the proprietary Sony Memory Stick formats, I also recommend avoiding the proprietary
xD-Picture card format wherever possible. Instead, I only recommend purchasing devices that use
industry standard memory card formats such as SD. Because of the backlash against proprietary
formats, Olympus and Fujifilm abandoned xD-Picture card in 2010.
SSD (Solid-State Drive)
In general, a solid-state drive (SSD) is any drive using solid-state electronics (that is, no mechanical
parts or vacuum tubes). Many people believe that SSDs are a recent advancement in computer
technology, but in actuality they have been around in one form or another since the 1950s, well before
PCs even existed.
Today, solid-state drives are used for many of the tasks magnetic and optical drives have traditionally
performed, including system drives, primary and secondary data storage, and removable-media
Virtual SSD (RAMdisk)
Although most people think of a physical drive when they discuss SSDs, these drives are available in
both physical and virtual form. A virtual SSD is traditionally called a RAMdisk because it uses a
portion of system RAM to act as a disk drive. The benefits are incredible read/write performance (it
is RAM, after all), whereas the drawbacks are the fact that all data is lost when the system powers
down or reboots, and that the RAM used for the RAMdisk is unavailable for the operating system
(OS) and applications.
RAMdisk software has been available for PCs since right after the PC debuted in late 1981. IBM
included the source code to a RAMdisk program (later called VDISK.SYS) in the March 1983 PC
DOS 2.0 manual, as part of a tutorial for writing device drivers. (Device driver support was first
implemented in DOS 2.0.) IBM later released VDISK.SYS as part of PC DOS 3.0 in August 1984.
Microsoft first included a RAMdisk program (called RAMDRIVE.SYS) with MS-DOS 3.2 (released
in 1986). Versions of RAMDRIVE.SYS were included in DOS and Windows versions up to
Windows 3.1, and a renamed version called RAMDISK.SYS has been included with Windows XP
and Windows 7/Vista. However, they are not automatically installed, and they are not well
documented. These DOS- or Windows-based RAMdisk programs are useful for creating high-speed
SSDs using existing RAM. As an alternative to using RAMDRIVE.SYS, you can use a variety of
commercial and freeware utilities available for Windows and for Linux. (See
http://en.wikipedia.org/wiki/List_of_RAM_drive_software for links to some of these utilities.)
Shortly after the release of the IBM PC in 1981, several companies developed and released physical
solid-state drives that could function as direct hard drive replacements. Many of these used
conventional dynamic or static RAM, with an optional battery for backup power, whereas others used
more exotic forms of nonvolatile memory, thus requiring no power to retain data. For example, Intel
had released “bubble” memory in the late 1970s, which was used in several SSD products. Bubble
memory was even included in the Grid Compass in 1982, one of the first laptops ever released.
Although SSDs can use any type of memory technology, when people think of modern SSDs, they
think of those using flash memory. Flash-based SSDs more recently started appearing in
commercially available laptop PCs from Dell, Asus, Lenovo, and others in 2007–2008. Since then,
many other laptop and desktop PC manufacturers have introduced systems with flash-based SSDs.
Ever since SSDs first became available for PCs in the early 1980s, many have thought that they
would universally replace hard drives. Well, it has been nearly 30 years since I first heard that
prediction, and it is just now becoming partially true. Until recently, the principle barriers preventing
SSDs from overtaking hard disks has been cost per GB and performance. Early SSDs were slower
than HDDs, especially when writing data, and performance would often fall dramatically as the drive
filled up. The development of controller hardware and operating systems optimized for SSDs have
enabled recent SSDs to surpass conventional hard disk drives in performance. Although SSDs are
still more expensive per GB than traditional hard disk drives, SSDs are now widely used for
applications where cost is not as important as performance and durability: Tablets, smartphones,
netbooks, and Ultrabooks use SSDs.
Many systems now strike a balance between the higher performance of SSDs and the greater capacity
of conventional hard disk drives by using both technologies. Many Ultrabooks use a small SSD
(32GB is a typical size) for the operating system and a conventional or hybrid SATA hard disk for
applications and system storage. Many high-performance desktop systems also use an SSD from
128GB to 512GB as a system drive, and a traditional hard disk for additional storage.
A hybrid SATA hard disk includes a small amount of flash memory used to cache mostfrequently-used information. To learn more, see Chapter 9.
Virtually all modern SSDs use the SATA (Serial ATA) interface to connect to the PC and appear just
like a standard hard disk to the system. Both 2.5-inch and 1.8-inch SSDs are shown in Figure 10.1.
Some high-performance SSDs come in a card-based form factor, usually designed for PCI Express
Figure 10.1. 2.5-inch and 1.8-inch solid-state drives (SSDs).
S LC Versus MLC
As previously mentioned, SSDs use NAND flash technology. Two subtypes of this technology are
used in commercially available SSDs: SLC (single-level cell) and MLC (multilevel cell). SLC flash
stores 1 bit in a single cell, whereas MLC stores 2 or more bits in a single cell. MLC doubles (or
more) the density, and consequently lowers the cost, but this comes at a penalty in performance and
usable life. SSDs are available using either technology, with SLC versions offering higher
performance, lower capacity, and higher cost. Most mainstream SSDs use MLC technology, whereas
more specialized high-end products (mostly for server or workstation systems) use SLC.
One major problem with flash memory is that it wears out. SLC flash cells are normally rated for
100,000 Write/Erase (W/E) cycles, whereas MLC flash cells are normally rated for only 10,000 W/E
cycles. When used to replace a standard hard drive, this becomes a problem because certain areas of
a hard drive are written to frequently, whereas other areas may be written to only a few times over
the life of the drive. To mitigate this wear, SSDs incorporate sophisticated wear-leveling algorithms
that essentially vary or rotate the usage of cells so that no single cell or group of cells is used more
than another. In addition, spare cells are provided to replace those that do wear out, thus extending
the life of the drive. Considering the usage patterns of various types of users, SSD drives are
generally designed to last at least 10 years under the most demanding use, and most last much longer
than that. As SSD capacity increases, so does the ability of the wear-leveling algorithm to spread out
data among available cells.
Note that, because of the way SSDs work internally, the concept of file fragmentation is immaterial,
and running a defragmenting program on an SSD does nothing except cause it to wear out sooner.
Unlike magnetic drives, which must move the heads to access data written to different physical areas
of the disk, an SSD can read data from different areas of memory without delay. The concept of the
location of a file becomes moot with wear leveling, in that even files that are presented as contiguous
to the file system are actually scattered randomly among the memory chips and cells in the SSD.
Because of this, SSDs should not be defragmented like traditional magnetic drives.
Windows 7 and 8 are SSD aware, which means they can tell an SSD from a standard magnetic
drive. These versions of Windows determine this information by querying the drive’s
rotational speed via the ATA IDENTIFY DEVICE command. (SSDs are designed to report
1rpm.) When Windows detects that an SSD is attached, it automatically turns off the
background Disk Defragmenter function, thus preserving drive endurance. When using SSDs
with Windows Vista and earlier versions, you should manually disable or otherwise prevent
any form of defragmentation program or operation from running on SSDs. For maximum
performance with any Windows version, install Tweak-SSD, available from
Another technique to improve SSD endurance and performance is an extension to the ATA interface
called the TRIM command. This allows an SSD-aware OS (such as Windows 7 or later) to
intelligently inform the SSD which data blocks are no longer in use, thus allowing the drive’s internal
wear leveling and garbage collection routines much more space to work with, which allows the drive
to maintain a high level of performance especially after all blocks have been written to at least once.
For this to work, both the drive and the OS must support the TRIM command. Windows 7 and Server
2008 R2 and later are SSD aware and support the TRIM command, whereas earlier versions of
Windows do not. SSDs released in 2009 or later generally support the TRIM command, whereas
those that do not may be able to add support via a firmware upgrade. When you are upgrading the
firmware on an SSD, it is highly recommended to have a full backup because in some cases a
firmware upgrade reinitializes the drive, wiping all data in an instant.
When an OS deletes a file or otherwise erases data from a drive, it doesn’t actually erase data.
Instead, the OS simply marks the file allocation or master file tables to indicate that those blocks are
available, while leaving the data in them untouched. This works fine on a normal HDD because
overwriting is the same as writing, but it greatly hinders a flash drive since a flash drive cannot
overwrite data directly. On a flash drive, any overwriting causes the drive to first write any
previously existing data to a new block, then erase the block, and finally write the new data. Over
time, this results in the SSD filling up and slowing down, even though from the OS point of view there
is a lot of empty space.
When TRIM is used, whenever a file is deleted, copied, or moved or the drive is reformatted, the
drive is immediately informed of all the blocks that are no longer in use. This allows the drive
controller to erase the unused blocks in the background, ensuring that there is always a sufficient
supply of erased blocks available to keep write performance at near like-new levels.
To further improve SSD performance, Windows 7 and later disable features such as Superfetch and
ReadyBoost as well as prefetching on SSDs with random read, write, and flush performance above a
When running a non-TRIM aware OS (Vista, XP, and earlier), you may still be able to take
advantage of TRIM by installing a TRIM-aware application. For example, Intel provides a program
called the Intel SSD Optimizer (part of the Intel SSD Toolbox) that you can periodically run to report
to the drive which files have been deleted. Other SSD manufacturers provide similar tools (often
called wiper.exe) as well. If you are running a non-TRIM aware OS with an SSD, check with the
SSD manufacturer to see if it has an optimization tool available.
Another issue with SSDs is that they are normally designed to read and write 4K pages and to erase
data in 512K blocks. Windows XP and earlier OSs normally start partitions 63 sectors into a disk,
which means that the OS file system components and clusters overlap pages and blocks, resulting in
more pages being read or written, and more blocks being erased than necessary, which can cause a
noticeable performance hit.
SSDs perform at their best when partitions are created with the SSD’s alignment needs in mind. All
the partition-creating tools in Windows 8/7/Vista place newly created partitions with the appropriate
alignment, with the first partition starting an even 2048 sectors into the disk. Because this is evenly
divisible by both 4K (8 sectors) and 512K (1024 sectors), there is no overlap between OS file
system cluster and SSD page/block operations.
Even if you are using Windows 8/7/Vista or another OS that normally creates aligned partitions, you
may still have misaligned partitions if the OS was installed into an existing partition or as an upgrade.
Many of the drive manufacturers have free partition alignment tools available that can check and even
correct the alignment of partitions on the fly. When creating new partitions on an SSD, you can
optionally use the DISKPART command to manually set the offset to the start of the first partition
such that all partitions on the drive will be properly aligned. With manual intervention, you can
ensure that even Windows XP and earlier will create partitions that are properly aligned for
S S D Applications
SSDs are ideal for laptops because they are more rugged (no moving parts), weigh less, and consume
less power. The weight savings is fairly minor because the difference between an SSD and a
conventional drive of the same (or even greater) capacity is generally only a few grams. The power
savings is more real—SSDs only draw about a tenth of a watt compared to about 1 watt for an HDD
(average). But even that may be overstated. Although drawing one-tenth the power sounds like a
considerable savings, compared to other components such as the CPU, GPU, and display, each of
which draw 30 watts or more, the overall power savings in going from a standard HDD to an SSD is
relatively low in comparison to the total power consumed.
SSDs are ideal as the boot drive for desktop systems because of their performance. Using an SSD can
drop boot or resume from hibernation times dramatically. SSDs are less ideal for storing large
amounts of data because capacities are less than what is available for conventional HDDs.
Will your next computer contain an SSD? If you buy a tablet, a netbook, or an Ultrabook, the answer
is “very likely.” SSDs are big enough to contain the operating system and applications and are rapidly
dropping in price per GB compared to magnetic storage. Netbooks, Ultrabooks, and other PCs can
use external hard disk drives or cloud-based storage for data storage, and some Ultrabooks include
both a small SSD for use by Windows and a larger hybrid hard disk (magnetic storage with a small
amount of flash memory) for application and data storage. Tablets can use flash memory slots, cloudbased storage, or both to supplement the capacity of an SSD.
USB Flash Drives
As an alternative to floppy and Zip/SuperDisk-class removable-media drives, USB-based flash
memory devices have rapidly become the preferred way to move data between non-networked
systems. The first successful drive of this type—Trek’s ThumbDrive—was introduced in 2000, and
since then hundreds of others have been introduced.
Some USB flash memory drives are even built into watches, pens, bottle openers, and knives
(such as the Victorinox SwissMemory Swiss Army Knife).
Unlike other types of flash memory, USB flash drives don’t require a separate card reader; they can
be plugged into any USB port or hub. Any system running Windows XP or later can immediately
recognize, read from, and write to a USB flash drive. As with other types of flash memory, USB flash
drives are assigned a drive letter when connected to the computer. Most have capacities ranging from
2GB to 64GB, but can be as large as 256GB with even larger capacities planned for the near future.
Typical read/write performance of USB 1.1-compatible drives is about 1MBps. Hi-Speed USB 2.0
flash drives are much faster, providing read speeds ranging from 5MBps to 15MBps and write
speeds ranging from 5MBps to 13MBps. SuperSpeed USB (USB 3.0) flash memory drives are now
available for USB 3.0 ports common on most modern desktops and laptops. Although some USB 3.0
flash memory drives support read/write performance up to 150MBps, the actual interface is designed
to support up to 625MBps (5Gbps). As controllers improve, future USB 3.0 flash memory drives are
likely to provide performance closer to the maximum speed of the interface. Because Hi-Speed and
SuperSpeed USB USB flash drives vary in performance, be sure to check the specific read/write
speeds for the drives you are considering before you purchase one.
USB 3.0 FAQ
Q. Does my computer support USB 3.0? How can I tell?
A. USB 3.0 ports use blue connectors and are typically marked with an SS next to the USB fork
icon. In Windows Device Manager, look for an eXtensible Host Controller Interface (XHCI)
controller entry in the Universal Serial Bus category.
Q. Will my new 32GB SupersSpeed USB thumbdrive run at SuperSpeed or HighSpeed if I use
A. A USB 3.0 drive must be connected to a USB 3.0 port to run at SuperSpeed (5Gbps). If a
USB 3.0 drive is connected to a USB 2.0 port, it runs at USB 2.0 speeds (HighSpeed
If you have a card reader or scanner plugged into a USB hub or port on your computer, you
might need to disconnect it before you can attach a USB flash drive. This is sometimes
necessary because of conflicts between the drivers used by some devices. If you suspect this
type of problem, use the Windows Safely Remove Hardware icon in the system tray to stop the
card reader before you insert the USB flash drive. After the system has recognized the USB
flash drive, you should be able to reattach the card reader.
For additional protection of your data, some USB flash drives have a mechanical write-protect
switch. Others include or support password-protected data encryption as an option, and most are
capable of being a bootable device (if supported in the BIOS). Some drives feature biometric
security—your fingerprint is the key to using the contents of the drive—whereas others include more
traditional security software.
Some companies have produced bare USB flash drives that act as readers for MMC, SD, xD-Picture
Card, Compact Flash, and Memory Stick flash memory cards. These USB flash readers are
essentially USB flash drives without flash memory storage onboard. You can use them as a card
reader or as a USB drive with removable storage.
Comparing Flash Memory Devices
As with any storage issue, you must compare each product’s features to your needs. You should check
the following issues before purchasing flash memory-based devices:
• Which flash memory products does your camera or other device support? Although adapters
allow some interchange of the various types of flash memory devices, for best results, you
should stick with the flash memory type your device was designed to use.
• Which capacities does your device support? Flash memory devices are available in everincreasing capacities, but not every device can handle the higher-capacity devices. Check the
device and flash memory card’s websites for compatibility information. In some cases,
firmware updates can improve a device’s compatibility with larger or faster flash memory card
• Are some flash memory devices better than others? Some manufacturers have added
improvements to the basic requirements for the flash memory device, such as faster write
speeds and embedded security. Note that these features usually are designed for use with
particular digital cameras only. Don’t spend the additional money on enhanced features if your
camera or other device can’t use those features.
Only ATA Flash cards can be attached directly to an older laptop computer’s PC Card slot. All other
devices need their own socket or some type of adapter to transfer data. Figure 10.2 shows how the
most common types of flash memory cards compare in size to each other and to a penny.
Figure 10.2. SmartMedia, CompactFlash, MultiMediaCard, Secure Digital, xD-Picture Card,
and Sony Memory Stick flash memory devices. Shown in relative scale to a U.S. penny (lower
Table 10.2 provides an overview of the major types of flash memory devices and their currently
available maximum capacities.
Table 10.2. Flash Memory Card Capacities