SD - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 210

Figure 12-2: USB flash drives
The i rst commercial product could hold 8 MB of data, more than i ve times
that of a l oppy disk. It was solid and robust, and could survive spending days
in a pocket, falling off desks, or being subjected to temperature differences. It
had a high transfer speed compared to l oppy disks (1 MB/second) and was
better than l oppies in almost all i elds.
In 2000, USB 1.1 was surpassed by USB 2.0, adding higher transfer speeds.
USB 2.0 could transfer up to 35 MB/s; huge i les could i nally be transferred
quickly and efi ciently. A second generation l ash disk used USB 2.0, which was
signii cantly faster than USB 1.1—approximately 20 times faster.
Speed increased and so did storage capacity. Every so often, capacities doubled.
Sixteen-megabyte versions were soon available, replaced by 32 megabytes, and
so on. Fourteen years later, terabyte-sized l ash drives are available. Despite their
huge growth and advances, l ash drives have remained relatively unchanged.
They rely on a small controller and l ash memory.
Flash memory is different from l oppies and hard drives. Floppy disks have
a thin, l exible disk of magnetic storage plastic, encased in a rigid plastic case.
A motor inside the disk drive turns the disk, and heads are placed above the
surface of the disk. To fetch data, the heads are placed at a specii c location and
the motor turns the disk. The heads read the data stored on the disk, but the