Zone bit recording
Zone Bit Recording is used by disk drives to store more sectors
Disk sector
In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512 bytes or 2048 bytes of user-accessible data per sector...

 per track
Cylinder-head-sector, also known as CHS, was an early method for giving addresses to each physical block of data on a hard disk drive. In the case of floppy drives, for which the same exact diskette medium can be truly low-level formatted to different capacities, this is still true.Though CHS...

 on outer tracks than on inner tracks. It is also called Zone Constant Angular Velocity
Constant angular velocity
In optical storage, constant angular velocity is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs...

(Zone CAV or Z-CAV or ZCAV).

On a disk consisting of concentric
Concentric objects share the same center, axis or origin with one inside the other. Circles, tubes, cylindrical shafts, disks, and spheres may be concentric to one another...

 tracks, the physical track length (circumference) is increased as it gets farther from the center hub. The inner tracks are packed as densely as possible, but with a CAV drive the data on the outer tracks are less densely packed. Using ZBR the drive divides all the tracks into zones and the inner track of each zone is packed as densely as possible with the other tracks in that same zone recorded with the same read/write rate. This permits the drive to have more bits stored in each track than not using this technique. More bits per track equates to more sectors per track.

On a hard disk using ZBR, the data on the tracks in the outer most zone will have the highest data transfer rate. This is where the operating system typically stores its own files. Testing disk drives when they are new or empty after defragmenting them with some benchmarking applications will often show their highest performance. After some time when more data is stored in the inner tracks, the data transfer rate in those zones will be slower; often making people think their disk drive is slowing down over time.

Some other ZBR drives, such as the 3.5" floppy drives in the Apple IIGS
Apple IIGS
The Apple , the fifth and most powerful model in the Apple II series of personal computers produced by Apple Computer. The "GS" in the name stands for Graphics and Sound, referring to its enhanced graphics and sound capabilities, both of which greatly surpassed previous models of the line...

 and older Macintosh
The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...

 computers, spin the medium faster when reading or writing inner tracks.

Products that use ZBR/ZCAV

  • Commodore 1541
    Commodore 1541
    The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...

     floppy disk
    Floppy disk
    A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

  • Apple Macintosh 400K/800K floppy disk
    Floppy disk
    A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

    DVD-RAM is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998.-Design:DVD-RAM is one of three competing...

  • HD DVD
    HD DVD
    HD DVD is a discontinued high-density optical disc format for storing data and high-definition video.Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format...

    -RW (note: not HD DVD-ROM or HD DVD-R)
  • Most hard drives since the 1990s
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