SELECTING OPTICAL DRIVES

There are only a few considerations in selecting an optical drive.

Interface

So far, internal drives come only in two interfaces: IDE and SCSI. IDE is the same interface as EIDE as it applies to hard drives, and thus the optical drives are connected to the same cables as the hard drives. See Chapter 6, “Magnetic Disk Drives,” for more information on the IDE interfaces. SCSI drives are simply additional devices in the SCSI chain. SCSI controllers and consequently, SCSI drives, are found almost exclusively in heavy-duty business computers. Serial ATA optical drives will be available eventually.

External drives once came with parallel interfaces (they connect to a parallel port on the computer) and SCSI, but now are available in USB and FireWire. You should select the fastest interface the user can afford. Also note that USB 2.0 is much faster than USB 1.1, so if you are using a USB 2.0 drive with a computer that has only a USB 1.1 interface, the drive will operate at the slower speed.

Speed

Speed of optical drives is based on the data transfer rate of the original CD-ROM drives, 150 kilobits per second (Kbps). For example, the data transfer rate of a 52x CD-ROM drive is 52 150, or 7.8 megabits per second (Mbps). Even the fastest optical drives, however, are slower than hard drives.

CD-RW Speed

A CD-RW, also known as a CD burner, has three speeds listed in its specifications. The first number represents the speed of writing to a CD-R, the second is the speed of writing to a CD-RW, and the third is the speed it reads a disc. In the case of a combo drive that offers a DVD-ROM along with a CD burner, a fourth number is the speed the drive reads a DVD, but see the next item for an explanation of DVD speeds.

DVD Speed

There are combo drives available that offer DVD and CD-burning capabilities. In these cases, there are so many numbers in the specifications that each is spelled out (or should be) wherever it is displayed. The single DVD-burning speed, however, is much faster than the CD’s 150 Kbps, and can vary from standard to standard. The actual speed in Mbps should be spelled out in the documentation.

Note

The maximum speed of the blank media (writable discs) in any format must match or exceed that of the burner in order for the burner to operate at its maximum rated speed.