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Glossary Hard Disk Drive Terminology: From Letter A to Letter Z. If you enjoy it, just add it to your favorite!

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Zoned Recording
Increases the number of sectors on the outer tracks of the drive since the circumference of the outside tracks is greater. This type of recording affords more disk capacity because there can be more sectors on the larger outer tracks than would be possible if the number of sectors per track were constant for the whole drive.

Year 2000 Problem, or Y2K
The risk that computers will be disabled or perform incorrectly if they read the two-digit abbreviation “00″ to mean the year 1900 instead of the year 2000, as intended. The problem is said to have originated when early computer programmers abbreviated year dates to save storage space that was scarce and costly at the time. Western Digital hard drives are designed to be “Year 2000-compliant,” and the company’ suppliers are required to demonstrate that their WD-linked communications and products are compliant as well.

WD Caviar®
The trade name for Western Digital’s line of hard drives for desktop personal computers.

WD Enterprise
The trade name for Western Digital’s line of enterprise hard drives.

Winchester Disk
Former code name for an early IBM hard disk model, sometimes still used to refer to the technology and design of most traditional hard drives.

Windows
Microsoft’s series of operating systems for personal computers. Currently popular versions are Windows 95 and Windows 98.

Word
Two bytes that are processed together in a single operation.

Workstation
A personal computer with exceptional capacity and performance capabilities for use mainly…

Value-added Reseller (VAR)
Often referred to as a “Var” or “Reseller.” The independent professionals who market computer systems and components and who add value by performing assembly, upgrades, training and other services.

Viterbi Detection
An algorithm used in read channel technology that detects an entire sequence of data bits at a time and determines the most likely sequence of data bits by comparing actual sequence of data bit samples with sequences of possible data bit sample to accurately detect that data written to disk.

Voice Coil
An actuator motor; the force of the magnetic rotary voice coil…

Ultra SCSI
Provides 20 MB/s transfers over an 8-bit bus or 40 MB/s transfers over a 16-bit Wide SCSI bus. Also known as Fast-20 SCSI, this feature is most commonly found in SCSI-3 drives.

Ultra DMA/33
A high-speed host data transfer feature that transfers data at 33.3 MB per second.

Un-correctable Error
An error that cannot be overcome using Error Detection and Correction.

Unformatted Capacity
The total number of usable bytes on a disk, including the space that is required to record location, boundary definitions, and servo data. (See also formatted capacity.)

Unrecoverable Error
A read…

Tagged Queuing
The ability of the drive to receive multiple I/O processes from each initiator.

Task File
The set of I/O Host Interface Registers used to transfer status, commands, and data between the host and the drive for the EIDE interface.

Thin Client Architecture
A computer system in which data is stored centrally, with only limited storage capacity at the various points of use.

Thin Film
A type of coating deposited on a flat surface through a photolithographic process. Thin film is used on disk platters and read/write heads, as well as on the write element of MR heads.…

SCA-2
SCA-2 (Single Connector Attach) interface incorporates a grounding contact, blindmate connector, direct plug misalignment tolerance, ESD protection, hot swap capability, and backplane connector options for SCSI devices. SCA-2 is commonly called the 80-pin SCSI connector.

Small Computer System Interface (SCSI)
An interface between a computer and peripheral controllers. Commonly used in enterprise computing and in Apple Macintosh systems. Usually pronounced as “scuzzy.” The equivalent interface system in most personal computers is Enhanced Integrated Drive Electronics, usually called EIDE.

SCSI Configure Automatically (SCAM)
Allows users to attach SCSI devices without worrying about configuration options.

SCSI-1
The Small Computer…

Radial Path
The straight-line path from the center of the disk to the outer edge of the disk.

Random Access Memory (RAM)
Memory that allows any storage location to be accessed randomly, as opposed to tape drives, which are sequential access devices.

Read Channel
Performs the data encoding and conversions the drive needs to write computer generated information onto a magnetic medium and then read that information back with a high degree of accuracy.

Read Verify
A data accuracy check performed by having the disk read data to the controller, which in turn checks for errors…

Qualification
The process by which sample components are tested for their compatibility and utility as parts of a system. Western Digital OEM customers qualify WD hard drives for use in their computers.

Queue
A first-in-first-out (FIFO) data structure used to sequence multiple demands for a resource such as a printer, processor, or communications channel. The host adds objects to the end of the queue and takes them off the front.