Upgrading And Repairing PCs 21st Edition: Flash Storage

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.

Note: 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 2 GB to 64 GB, but can be as large as 256 GB with even larger capacities planned for the near future. Typical read/write performance of USB 1.1-compatible drives is about 1 MB/s. Hi-Speed USB 2.0 flash drives are much faster, providing read speeds ranging from 5 MB/s to 15 MB/s and write speeds ranging from 5 MB/s to 13 MB/s. 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 150 MB/s, the actual interface is designed to support up to 625 MB/s (5 Gb/s). As controllers improve, future USB 3.0 flash memory drives are likely to provide performance closer to the maximum speed of the interface (Ed.: Minus encoding overhead). 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.


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 32 GB SupersSpeed USB thumbdrive run at SuperSpeed or HighSpeed if I use 2.0 ports?

A. A USB 3.0 drive must be connected to a USB 3.0 port to run at SuperSpeed (5 Gb/s). If a USB 3.0 drive is connected to a USB 2.0 port, it runs at USB 2.0 speeds (Hi-Speed 480 Mb/s).

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 on-board. You can use them as a card reader or as a USB drive with removable storage.

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