Lenovo ThinkPad 770Z DVD Information Brief

DVD: think of it as CD-ROM

—

but bigger, faster, and even more versatile

DVD Optical Storage

Information Brief

Worth remembering

DVD can store up to 17GB

1

of data in a robust optical format

The first DVD drives were read-only devices, or DVD-ROM

The DVD format should spark innovative multimedia applications for business featuring

full-screen, full-motion MPEG-2 digital video and Dolby Digital™ surround sound

Planned DVD enhancements include write-once (DVD-R) and rewritable versions

(DVD-RAM) available in 1997 or 1998

Overview

There’s no doubt about it—DVD is poised to revolutionize both the home electronics and com-

puter industries. DVD has the look and feel of today’s familiar audio CDs and CD-ROM discs

(4.75-inch/120mm) that store music and computer software. For the computer industry, DVD de-

livers up to 17GB of storage, 25 times the current data capacity of CD-ROM. (A 3" variant of the

format has also been proposed with 2.6GB of storage per side.) DVD drives are backward-

compatible with audio CD, CD-ROM, CD-i and PhotoCD. DVD-R (write once recordable) tech-

nology should be introduced by late-summer 1997, followed by DVD-RAM (write many) in 1998.

For digital video storage, DVD uses the MPEG-2 compression scheme to accommodate the huge

storage demands of high-quality feature length movies.

Inside DVD technology

Originally named “Digital Video Disk,” then “Digital Versatile Disk,” the format is now simply

and officially “DVD” with no three-word-equivalent. DVD has become an industry standard

thanks to the efforts of Sony, Toshiba, Phillips, IBM and other companies. IBM chaired the com-

puter industry technical working group that was responsible for defining the requirements of

DVD for the computer industry. IBM helped bridge the gap between two opposing factions who

had proposed incompatible formats. The brokered agreement sets forth a universal standard,

avoiding a replay of the VCR marketing war between proponents of the VHS and Beta formats.

Like CD-ROM, the DVD format is read by an infrared laser focused through a protective plastic

layer onto the disc’s reflective layer. (The transparent layer is 1.2mm thick on a CD-ROM, but

only .6mm on a DVD-ROM.)

The beam reflects off pits burned into the reflective layer by the

recording laser and is passed through optics to the pickup. The laser beam utilized on a CD-ROM

player has a wavelength of 780 nanometers (.78 millionth of a meter). DVD players employ a

September 1997