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CompTIA A+ Certification All-in-One Exam Guide

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CD-ROM Speeds The first CD-ROM drives processed data at roughly

150,000 bytes per second (150 KBps), copying the speed from the original

CD-audio format. Although this speed is excellent for listening to music, the

CD-ROM industry quickly recognized that installing programs or transferring

files from a CD-ROM at 150 KBps was the electronic equivalent of watching

paint dry. Since the day the first CD-ROM drives for PCs hit the market,

there has been a desire to speed them up to increase their data throughput.

Each increase in speed is measured in multiples of the original 150-KBps

drives and given an × to show speed relative to the first (1×) drives. Here’s a

list of the common CD-ROM speeds, including most of the early speeds that

are no longer produced:

CD-R Making CD-ROMs requires specialized, expensive equipment and

substantial expertise, so a relatively small number of CD-ROM production

companies do it. Yet, since the day the first CD-ROMs came to market,

demand was high for a way that ordinary PC users could make their own

CDs. The CD industry made a number of attempts to create a technology that

would let users record, or burn, their own CDs.

In the mid-1990s, the CD industry introduced the CD-recordable (CD-R)

standard, which enables affordable CD-R drives, often referred to as CD

burners, to add data to special CD-R discs. Any CD-ROM drive can then

read the data stored on the CD-R, and all CD-R drives can read regular CD-

ROMs. CD-R discs come in two varieties: a 74-minute disc that holds

approximately 650 MB, and an 80-minute variety that holds approximately

700 MB (see Figure 10-52). A CD-R burner must be specifically designed to

support the longer, 80-minute CD-R format, but most drives you’ll encounter

can do this.

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