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In the history of optical storage media there have been and there are different optical disc formats with different data writing/reading speeds.. Original CD-ROM drives could read data at about 150 kB/s, 1× constant angular velocity (CAV), [1] the same speed of compact disc players without buffering.
Unlike early CD-ROM drives, optical disc recorder drives have generally used industry standard connection protocols. Early computer-based CD recorders were generally connected by way of SCSI ; however, as SCSI was abandoned by its most significant users (particularly Apple Computer ), it became an expensive option for most computer users.
Some optical drives additionally throttle the reading speed based on the contents of optical discs, such as max. 40× CAV (constant angular velocity) for the Digital Audio Extraction (“DAE”) of Audio CD tracks, [32] 16× CAV for Video CD contents [33] and even lower limitations on earlier models such as 4× CLV (constant linear velocity ...
CD-R recording systems available in 1990 were similar to the washing machine-sized Meridian CD Publisher, based on the two-piece rack mount Yamaha PDS audio recorder costing $35,000, [citation needed] not including the required external ECC circuitry for data encoding, SCSI hard drive subsystem, and MS-DOS control computer.
It uses the Disc-At-Once method, usually at 1x, but some recorders allow for 4x and 8x speed mode. Since the pits and lands are longer, the quantity of information that can fit on a disc is less than with a normal method: 63 minutes instead of 74 minutes on a 650MB CD or 68 min instead 80 minutes on a 700MB CD.
As the motor's speed decreases from 1,800 to 600 rpm when the read head moves away from the center (which is the start of the recording), the disc moves past the read head at a constant speed. Later optical formats such as the audio CD also employ CLV to maintain both a constant data rate and a constant bit density.
In optical storage, constant angular velocity (CAV) is a qualifier for the rated speed of any disc containing information, and may also be applied to the writing speed of recordable discs. A drive or disc operating in CAV mode maintains a constant angular velocity, contrasted with a constant linear velocity (CLV).
Russell's first optical disc was distinctly different from the eventual compact disc product: the disc in the player was not read by laser light. A key characteristic of Russell's invention is that a laser is not used for the reading the disc, instead the entire disc or oblong sheet to be read is illuminated by a large playback light source at ...