A CDE Definition
zoned constant angular velocity
(1) (Component Analog Video) See YPbPr.
(2) (Constant Angular Velocity) Rotating an optical disc or hard disk at a constant speed. Contrast with "constant linear velocity" (CLV), in which the platter rotates at varying speeds. Since the circumferences of the inner tracks on a disk are smaller than the outer tracks, if a single clock frequency is used to write the data, the inner tracks are more dense than the outer ones in a CAV system.
Zone Bit Recording
In order to maximize the space on a round medium more efficiently, in the 1990s, hard drive manufacturers migrated to "zone CAV" (Z-CAV), also known as "zone bit recording" (ZBR). Z-CAV breaks the disk into multiple zones that each contain several thousand tracks, the number depending on the zone's location within the platter. When the read/write head moves from zone to zone, the clock frequency changes. As a result, the outer tracks have more sectors than the inner tracks and hold more data, and the disk's capacity is larger for the same size platter.
Just Two Zones
"Partial CAV" (P-CAV), also known as "CAV/CLV," breaks the disk into two zones. Used in certain CD-ROM and DVD drives, P-CAV keeps the speed constant for the inner zone (CAV), but varies the disk rotation for the outer zone (CLV). See CLV.
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