Hardware Reference
In-Depth Information
the section “
MultiRead Specifications
,
” earlier in this chapter, for more information. Al-
though the MultiRead2 logo is not used on current products, some recent and current
DVD-ROM drives can read DVD-RAM media; check the specification sheet for a partic-
ular drive to verify compatibility.
The first DVD-RAM drives were introduced in spring 1998 and had a capacity of 2.6GB
(single-sided)or5.2GB(double-sided).DVD-RAMVersion2discswith4.7GBarrivedin
late1999,anddouble-sided9.4GBdiscsarrivedin2000.DVD-RAMdrivestypicallyread
DVD-Video, DVD-ROM, and CD media. Although DVD-ROM drives, older DVD+R/
RWandDVD-R/RWdrives,andDVD-Videoplayerscan'treadDVD-RAMmedia,DVD
Multi and DVD Super Multi drives can read/write DVD-RAM.
DVD-RAM uses what is called the
wobbled land and groove recording
method, which
records signals on both the lands (the areas between grooves) and inside the grooves that
are preformed on the disc. The tracks wobble, which provides clock data for the drive.
Special sector header pits are prepressed into the disc during the manufacturing process
as well. See
Figure 11.13
, which shows the wobbled tracks (lands and grooves) with data
recorded both on the lands and in the grooves. This is unlike CD-R or CD-RW, in which
data is recorded on the groove only.
Figure 11.13
DVD-RAM wobbled land and groove recording.
