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For further discussion of risks related to our development of new products, see Item 1A of this Annual Report on
Form 10-K.
Technology and Product Development
Hard drives record, store and retrieve digital data. Performance attributes of hard drives, such as their ability to
access and transmit data and storage capacity, are currently better than removable or floppy disks, optical hard drives and
tapes, and they are more cost effective than semiconductor technology. The primary measures of hard drive performance
include:
• “Acoustics” — which is the sound power emitted during hard drive operation, commonly expressed in decibels.
• “Data transfer rate” — which is the sustained rate of data transfer to and from the disk, commonly expressed in
megabits per second. One megabit equals one million bits.
• “Seek time” — which is the time needed to position the heads over a selected track on the disk surface, commonly
expressed in milliseconds.
• “Spindle rotation speed” — which is the nominal rotation speed of the disks inside the hard drive, commonly
expressed in RPM, revolutions per minute or latency. Spindle rotation speeds commonly stated as 5,400, 7,200
and 10,000 RPM are sometimes approximations.
• “Storage capacity” — which is the amount of data that can be stored on the hard drive, commonly expressed in
GB or TB. As defined in the hard drive industry, one GB equals one billion bytes and one TB equals one trillion
bytes. A byte is a digital character, typically comprised of eight bits. A bit is a binary digit, the smallest unit of
information in a digital system.
All of our hard drive products employ similar technology. The main components of the hard drive are a head disk
assembly and a printed circuit board. The head disk assembly includes heads, media (disks), head positioning mechanism
(actuator) and spindle motor. A rigid base and top cover contain these components in a contamination-controlled
environment. The printed circuit board includes both standard and custom integrated circuits, an interface connector to
the host computer and a power connector.
One or more disks positioned around a motor-driven spindle hub that rotates the disks comprise the head disk
assembly. A thin coating of magnetic materials applied to a smooth substrate make the disk. Each disk has a head
suspended directly above it, which can read data from or write data to the spinning disk.
The integrated circuits on the printed circuit board typically include a drive interface and a controller. The drive
interface receives instructions from the computer, while the controller directs the flow of data to or from the disks and
controls the heads. The location of data on each disk is logically maintained in concentric tracks divided into sectors. The
computer sends instructions to the controller to read data from or write data to the disks based on logical track and sector
locations. Guided by instructions from the controller, the head stack assembly pivots and swings across the disk by a head
actuator or motor until it reaches the selected track of a disk, where the data is recorded or retrieved.
Industry standard interfaces allow the hard drive to communicate with the computer. Currently, the primary
interfaces for PCs are EIDE and SATA, and the primary interfaces for enterprise systems are SCSI, SATA, SAS and FCAL.
As computer performance continues to improve, the hard drive will need to deliver information faster. We believe this
will continue to drive the PC industry transition to higher speed interfaces, such as SATA, to handle the higher data
transfer rates. We currently offer our WD Caviar»and WD Caviar»GreenPower
TM
(“GP”) drives with the SATA interface
featuring capacities as large as 750 GB and 1 TB, respectively. We design these products for the PC, workstation, and
external storage markets. We currently offer our WD Raptor», a 10,000 RPM enterprise-class drive with the
SATA interface, and the WD RE, 7,200 RPM drives manufactured to enterprise-class standards and available with
a SATA interface.
The number of disks and each disk’s areal density, which is a measure of the amount of data that can be stored on the
recording surface of the disk, determines storage capacity of the hard drive. The higher the areal density, the more
information can be stored on a single platter. Achieving a given drive capacity requires fewer disks as the areal density
increases, potentially reducing product costs over time through reduced component requirements. Beginning in June
9