Quenching storage thirst - computer storage; includes related article

Black Enterprise, Jan, 1993 by Carolyn M. Brown

The insatiable thirst for more computer has ignited the explosion of CD-ROM drives. And while the popularity of CD-ROMs may seem faddish, it is not likely to fade.

With the PC standard, you could have hundreds of megabytes of information at your fingertips. But then you probably would have to stuff your hard drive almost to the breaking point. No matter how large your drive, there just never seems to be enough room. Who isn't used to deleting or copying old files from the hard drive to make way for new ones?

Make way for CD-ROM (Compact Disk Read Only Memory) drives as an escape from the cluttered world of hard drives. CD-ROM ultimately turns your PC into an unlimited information base.

Disks that hold library references, entertainment and education programs are arriving in force and are providing high-quality graphics, sound and animation. Many manufacturers are now using CD-ROM to supply software. Consider this: It takes four or more floppy disks to hold an integrated software package with a spreadsheet, word processing and database program. But all three programs can be stored on a single CD-ROM disk, which employs optical disk technology.

A single CD-ROM disk can hold more than 650 MBs of information. That translates into more than 300,000 typed pages. Just think, an entire encyclopedia, including pictures, fits on one CD-ROM disk.

Ultimately, sound and video will be built into most computers and considered essential for all business applications. Add a sound board, speaker system and CD-ROM drive to your computer and you have entered the wonderful world of multimedia. Such capabilities allow a PC to sound off, talk to and interact with its user.

Cousin To The Audio Compact Disc

CD-ROM players are best described as audio CD players with extra features. With a CD-ROM drive, you could listen to music while crunching numbers for a major report. But you need the appropriate software to play the audio files from the disk plus a pair of earphones or amplified speakers.

This pumped up CD player obviously costs much more. If you recently bought a decent audio player for about $200, tack on about four times that price for a CD-ROM drive. The cost disparity is partly because the CD-ROM market is much smaller than the CD audio market. So, the economy of scales keeps prices low for audio CD players.

CD-ROM players also have more advanced components. The system consists of an adapter card, usually an SCSI (small computer interface), cable and the drive itself. There are both internal and external drives on the market, although the latter is much easier to install. Since an audio CD player has no SCSI interface, you can't hook it up to a personal computer.

Essentially, a CD-ROM drive looks and feels like a hard disk. But then you can't write data to CD-ROM. When you purchase a CD-ROM disk, it already has files on it--no more files can be added on.

And compared with a fast-fixed hard drive, CD-ROM is slow. Even the fastest CD-ROM drives have turtle like performance when it comes to accessing information from the drive.

The time it takes to find random information is measured in milliseconds (ms). The average access time of most CD-ROM drives is 300 ms to 600 ms. This pales in comparison with the 16ms you'll get with a fast PC hard drive, which makes it about 18 to 38 times faster than CD-ROM.

The transfer rate, or the amount of time it takes the drive to transfer data to the CPU (central processing unit) is measured in Kbps, or kilobytes per second. CDs offer a narrow pipeline for transmitting large data files. So, at 150 Kbps, the standard transfer rate for a CD audio file would take a couple of minutes to transfer data to a 10 MB file.

Access time is critical in an application like an encyclopedia, dictionary or database where the drive spends most of its time searching data. Transfer rate matters especially to folks using multimedia. In this case, finding information often takes a back seat to transferring it rapidly and smoothly to the CPU for display.

But performance is more than access speed and data transfer rates. The driver software, which mediates between the drive and the CPU is another factor. A faster CD-ROM drive makes a big difference, for instance, when running Apple QuickTime movies, accessing photo databases or playing interactive computer games. Reliability, ease of setup, audio support, bundled software, price and technical support are equally important over the long haul.

Three top CD-ROM drives that have earned best buy ratings from PC World magazine are NEC's CDR-73M, Toshiba's TXM-3301E and Sony's CDU-7205 Laser Library.

NEC's unit exceeds the standard 150 Kbps data transfer rate at 300 Kbps. This drive, which retails for $765, also has a 280 ms average random access time for text searches. Considered a leader in the pack of quick multimedia-ready drives, Toshiba offers its TXM-3301E for $950. And Sony's Laser Library CD-ROM System CDU-7205 brings the world to home computer users. This unit, which retails for $699, comes bundled with various reference materials, ranging from an encyclopedia and an atlas to language programs.