Upgrading & Fixing Laptops DUMmIES

The typical access speed of a 1X drive was about 400 ms with a throughput of

150 kilobytes per second; a modern 52X drive may be able to get into position

to access data in an average of about 85 ms and pump data to the computer

at as much as 8MB per second.

Now when it comes to recording a disc, the write speed can have a major effect

on the time required to burn a disc. An original 1X CD required about 74 min-

utes to record 650MB of data; a CD-R capable of a 48X recording speed could fill

that disc in about 90 seconds.

Doing DVDs and DVD-Rs..............................................................................

The story of the DVD closely parallels that of the CD. It was first envisioned

as a digital improvement on the analog videocassette as a medium to distrib-

ute movies and other video. But once it was adopted by the general public

as a fabulous way to watch the latest thriller or comedy in high-, stop-action

quality, the economy of scale brought the price of production down to the

point where DVD players could be installed in laptop computers.

Not long after DVDs became nearly ubiquitous in home entertainment systems,

engineers developed ways to allow users to record their own discs. Recordable

DVDs have arrived in versions that can be used on computers, and also as a

replacement for VCRs to make copies of television broadcasts.

The consumer side of the equation was responsible for the first specification

for DVDS that received widespread use: a single-sided single layer with a

capacity of 4.7GB. It just so happens that that size can accommodate a two-

hour motion picture, complete with stereo audio and special video features.

Engineers have designed compression schemes for audio and video that

permit stereo surround sound, subtitles, and widescreen or letterbox ver-

sions of films.

And most recently, designers have figured out ways to produce multiformat

devices for computers and laptops:

CD and DVD combination players

CD-R and DVD players

CD-R and DVD-R devices

DVDs and CDs have more in common than they have differences; DVDs are,

though, considerably larger in their capacity and their potential for advanced

applications. While a CD maxes out at about 800MB in capacity, DVDs can

presently hold about 4.7 or 9.4GB, and designs call for a doubling and tripling

of that already stupendous size.

Chapter 9: Going Round and Around: CD and DVD Drives 153