CHAPTER 13

702 Chapter 13 Optical Storage
Table 13.6 CLV Versus CAV Technology Quick Reference
CLV (Constant Linear Velocity) CAV (Constant Angular Velocity)
Speed of CD rotation: Varies with data position on CD— Constant
faster on inner tracks than on outer tracks
Data transfer rate: Constant Varies with data position on CD—
faster on outer tracks than on inner tracks
Noise level: Higher Lower
CD-ROM drives have been available in speeds from 1x up to 56x and beyond. Most nonrewritable
drives up to 12x were CLV; most drives from 16x and up are CAV. With CAV drives, the track data is
moving past the read laser at various speeds, depending on where the data is physically located on
the CD (near the inner or outer part of the track). This also means that CAV drives read the data at
the edge of the disk more quickly than data near the center. This allowed for some misleading
Table 13.7 CD-ROM Drive Speeds and Transfer Rates
Column 1 Column 2 Column 3 Column 4 Column 5 Column 6
Time Time Transfer Actual Minimum
Advertised to Read to Read Rate CD-ROM Speed Transfer
CD-ROM Speed 74-minute 80-minute (Bytes/sec) Minimum Rate if CAV
(Max. if CAV) CD if CLV CD if CLV (Max. if CAV) if CAV (Bytes/sec)
1x 74.0 80.0 153,600 0.4x 61,440
2x 37.0 40.0 307,200 0.9x 138,240
4x 18.5 20.0 614,400 1.7x 261,120
6x 12.3 13.3 921,600 2.6x 399,360
8x 9.3 10.0 1,228,800 3.4x 522,240
10x 7.4 8.0 1,536,000 4.3x 660,480
12x 6.2 6.7 1,843,200 5.2x 798,720
16x 4.6 5.0 2,457,600 6.9x 1,059,840
20x 3.7 4.0 3,072,000 8.6x 1,320,960
24x 3.1 3.3 3,686,400 10.3x 1,582,080
32x 2.3 2.5 4,915,200 13.8x 2,119,680
40x 1.9 2.0 6,144,000 17.2x 2,641,920
48x 1.5 1.7 7,372,800 20.7x 3,179,520
50x 1.5 1.6 7,680,000 21.6x 3,317,760
52x 1.4 1.5 7,987,200 22.4x 3,440,640
56x 1.3 1.4 8,601,600 24.1x 3,701,760