Land or Pits

Mass produced CD-ROM are a stamped media with indentations physically stamped into the recording layer of the media which is then covered by a hard clear plastic. A laser beam focused at these indentations reflects differently than the parts of the media that are not indented. The indentations are called “Pits.” “Land” is the area that is not indented. Rather than use actual Pits and Land CD-R and CD-RW use heat to alter the reflectivity of the chemical of the recording layer. A laser optical device can read the difference in reflectivity of different states of these chemicals, much like reading the difference in reflectivity of the Land and Pits in a stamped CD.

Lead in

Session information written at the beginning of a session.

Lead out

Session information written at the end of a session.

LED

Light Emitting Diode. A light device that is designed to not burn out

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Mb

Megabyte. Basically means one million bytes, but is actually 1024 kilobytes or 1024 X 1024 bytes which is 1,048,576 bytes.

Mb/s

Megabytes per second. Means of measuring throughput.

Megabyte

see Mb.

Multi-Read

The ability for CD-ROM, CD-R, CD-RW, and DVD-ROM drives to read CD-ROM, CD-R and CD-RW media.

Multi-Session

Multi-Session means several sessions can be written to, and read from CD-ROM, CD-R or CD-RW media.

PC

Personal Computer. Sometimes also a term for IBM PC or Windows Compatible PC. In this user’s guide the term “PC” means Windows or Windows NT compatible PC, as opposed to Macintosh, or a UNIX based computer.

Phase Change

The ability of a substance to change states and then be stable in the new state. In CD-RW media the recording layer can change from an amorphous state which does not reflect strongly to a crystalline state which does reflect strongly. See Reflectivity.

Pits or Land

See Land or Pits.

Real Time Transfer Mode

The ability to present sound and image at the same speed they were recorded.

Record a CD

Burn a CD, Writing a CD. Uses special CD- Recordable discs which can be altered by the laser in a CD-R drive.

Reflectivity

In the sense of laser optical devices, differences in reflectivity can be read as 0 and 1 bits. The intensity of a laser will reflect differently from a crystalline, glass like state, than an amorphous, or non-crystalline, state. Much like a flashlight will reflect more brightly from a mirror than from a white painted wall.

Session

Data written to CD-R media at one time.

Source drive

The drive which contains information that will be written somewhere else. In CD recording the source drive contains the information that will be written to the CD Recorder.

Sustained transfer

The rate which data can be transferred from one device to another. This rate is an average over a longer period of time than a burst transfer rate.

Because the sustained transfer test is longer, it means the testing will take into account both reading or writing from the storage device’s buffer, as well as from the media. Reading and Writing from the media is a much slower operation, so the sustained transfer test is usually a much better test for determining the usability of a device in a real application, such as recording a CD.

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