Chapter 1

mat, which held 3 billion bytes (2.8 gigabytes) per side and was not compatible
with any existing players and drives, was abandoned in late 1999.
The DVD�RW format uses phase-change media with a high-frequency
wobbled groove that allows it to eliminate linking sectors. This, plus the
option of no defect management, allows DVD�RW discs to be written in a
way that is compatible with many existing DVD readers. The DVD�RW
specification allows for either CLV format for sequential video access (read
at CAV speeds by the drive) or CAV format for random access, but CAV
recording is not supported by any current hardware. DVD�R discs can only
be recorded in CLV mode. Only CLV-formatted discs can be read in standard
DVD drives and players. DVD�RW media can be rewritten about
1,000 times (down from 100,000 times in the original 1.0 version).
DVD�R is a write-once variation of DVD�RW, which appeared in mid
2002. It’s a dye-based medium, like DVD-R, so it has similar compatibility
as DVD-R. Original DVD�RW drives did not fulfill the promise of a simple
upgrade to add DVD�R writing support, so they have to be replaced with
newer models. The original Philips DVD�RW video recorders, on the other
hand, can be customer-upgraded to write �R discs.
Philips announced a DVD�RW home video recorder for late 2001. The
Philips recorder uses the DVD-Video format, so discs play in many existing
players. HP announced a $600 DVD�RW drive (made by Ricoh) and $16
DVD�RW discs for September 2001. HP’s drive reads DVDs at 8x and CDs
at 32x, and writes to DVD�RW at 2.4x, CD-R at 12x, and CD-RW at 10x.
In 2003 DVD�R discs cost around $2 to $6 and DVD�RW discs cost
around $5 to $10. DVD�RW media are produced by CMC Magnetics,
Hewlett-Packard, MCC/Verbatim, Memorex, Mitsubishi, Optodisc, Philips,
Ricoh, Ritek, and Sony.
More DVD�RW information is at www.dvdrw.com and www.
dvdplusrw.org. The obsolete DVD�RW 1.0 format is standardized in
ECMA-274.
Other Recordable Optical Formats
DVDs and Computers 129
Competitors to recordable DVD were announced but never appeared,
thanks in part to the success of the entire DVD family. These formats
included AS-MO (formerly MO7), which was to hold 5 to 6 billion bytes, and
NEC’s Multimedia Video Disc (MVDisc, formerly MMVF, Multimedia Video
File), which was to hold 5.2 billion bytes and was targeted at home recording.
ASMO drives were expected to read DVD-ROM and compatible
writable formats, but not DVD-RAM. MVDisc was similar to DVD-RW and
DVD�RW, using two bonded 0.6mm phase-change substrates, land and