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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
.
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.