Glossary

Access times

The average amount of time to access an item of data.

Amorphous

Lacking shape, or in mineral terms, not crystalline. Amorphous could be taken to mean a liquid or gel like state. In terms of CD-RW the important aspect is that the material will remain stable in this state (not change out of this state unless acted upon by an outside force of great heat) AND that the amorphous state has a different reflective quality than in a crystalline state.

Analog

(as opposed to digital) where digital is defined discrete items which can be reduced to zero and one bits. Analog is continuous, so on any graphic representation of analog data there are an infinite number of points between any two points. Digital approximates analog by adding data points.

Archive

To save files or records, usually in a safe place, for later retrieval.

ATAPI

AT Compatible Attachment Packet Interface. An enhancement to EIDE which allows CD-ROM type devices to use the EIDE interface.

Bi-directional Cable

Signals can transfer both ways on the same cable, rather than requiring a separate cable for each direction, as with video in and video out.

Buffer

RAM Cache that is faster than the data is being delivered. Buffers are used so data may be stored and delivered to the receiving item as it is needed.

Buffer Underrun

When a function (such as writing to CD-R media requires a constant stream of data), attempts to pull data faster from the buffer than data can be input from a source drive, and the data buffer becomes empty.

Burn a CD

Recording a CD-R. Because a laser is used to write a CD it is also known as burning a CD.

Burst transfer

The fastest a device can transfer, usually from its buffer.

CAV

Constant Angular Velocity. Constant Angular Velocity means the drive or media spins at a constant rate, rather than spinning faster or slower as was common with older CD-ROM devices which used CLV (Constant Linear Velocity). CLV drives cause performance degradation at higher speed because there is a lag time, or latency period, before the drive reaches a standard readable speed for each track. See CLV.

CD-R drive

A drive that can write to recordable CD-R media.

CD-RW drive

A drive that can write to recordable CD-R and Rewritable CD-RW media.

CD-ROM drive

A drive that can read from CD media.

CLV

Constant Linear Velocity. Rotating a disc at such a rate to keep the length of track read at a constant speed. Since a track at the outside of a circle is much longer than tracks near the center, the outside track will be moving faster than interior tracks for each revolution. To keep the length of track read at the same speed, CLV drives speed up when reading tracks near the center and slow down when reading tracks near the outside. Older CD-ROM devices use CLV.

Crystalline

The recording material can be made to stabilize in a crystalline state with greater reflective qualities than the amorphous state. See Amorphous.

Data stream

The flow of data that accomplishes a task, usually related to moving data from storage to computer RAM or between storage devices.

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