CD-ROM: an on-ramp to the information superhighway

Medical Laboratory Observer, Jan, 1995 by Seth L. Haber

ONE OF THE FIRST effective on-ramps to the promised great information superhighway is the wealth of CD-ROMs currently available in MS-DOS and Windows formats and for the Macintosh. If you are computer literate and not using CD-ROMs, you're missing the chance to keep more data available at your fingertips than are found in some small libraries. Approximately 8 million CD-ROM players were sold in the United States last year, bringing to 15 million the total number in use in this country. Within 5 years, more than 75% of computers will have CD-ROM players.

* Playing information. CD-ROMs work on the same digital principle as the CDs (compact disks) that play music. In this case, however, the spinning disk plays information that often includes pictures and multimedia presentations. ("Multi-media" is computerese for what used to be called audiovisual--incorporating slides, movies, and music or other sounds.)

A CD-ROM can hold about 650 Mb of information. That is equivalent to nearly 500 floppy disks, enough space to store:

* A 24-volume encyclopedia (Britannica, Compton's, or Grolier's, for example)

* The 20-volume Oxford English Dictionary

* Scientific American Medicine together with CME quizzes

* Several years of the Medline subsets available through the National Library of Medicine (NLM)

ROM is an acronym for read only memory. This means that you cannot write on a CD-ROM. What you've bought is what you've got; they're locked disks. Right now, there are almost 8,000 CD-ROM titles available. Some 500 are low-cost retail programs, including games, fonts, pictures, encyclopedias, and databases of interest to the general public. These programs sell for from $30 to $200. Specialty disks, such as those that the NLM makes available to commercial packagers to sell to physicians, cost from $300 to $800. Additionally, there are thousands of specialized business databases, each one selling for from $500 to $5,000.

* Necessary hardware. Of course, you'll need a CD-ROM player. These are more expensive than the ones used to play music because they do not play tracks consecutively. They need a very precise stepping motor to place and keep the head in the exact position on the disk. The CD-ROM player can play music well, but not the reverse. The new "double-speed" CD-ROMs (actually, about 1.5 times as fast as standard drives) are just slightly slower than your hard disk. Triple (about 2 times as fast as standard) and quadruple speed (about 3 times as fast) CD-ROM players are very expensive and probably more than you need.

Most players handle one disk at a time. Those with built-in changers are so expensive that it is almost better to daisy-chain a stack of single disk players. All but a few players require that you first place the disk in a protective caddy (such as CD Caddy, from CD Technology, Sunnyvale, Calif.), which is about the size and shape of the "jewel box" that music CDs come in and costs between $5 and $7. Rather than risk scratching the expensive disks while shuffling them in and out of boxes, you'll probably want to buy one caddy for each CD.

* Author's preferences. Which player would I buy? For the Macintosh, I think the AppleCD 300e (between $350 and $500 from Apple Computers, Cupertino, Calif., or an authorized reseller) is best. If you need multiple-disk capability, the Pioneer DRM-604X (between $1,400 and $1,800 from Pioneer Electronics, Long Beach, Calif. or an authorized dealer) can hold six disks. I would still rather daisy-chain several AppleCD 300es. They are easily available at deeper discounts, and I don't need instant access to six CD-ROMs. The AppleCD 300e is simpler and less apt to fail; if one unit goes down, you still have the others.

I also prefer an external CD-ROM player to one that's built into your computer. When an external drive fails, you don't have to give up your whole PC during repair.

* Medical software. Let's discuss CD-ROMs of particular interest to technologists, pathologists, and other physicians. My favorite and most frequently used CD-ROM disks are the Aries Knowledge Finder series (various prices from Aries Systems Corp., North Andover, Mass.). By using this resource, you can easily search through:

* The hundreds of journals on NLM's Medline

* A core group of journals

* Subsets chosen for particular interest to subspecialists such as pathologists (PathLine), internists, surgeons, pediatricians, oncologists, orthopedists, or physicians caring for patients with AIDS

Whereas a disk of the unabridged Medline may hold only 2 years of abstracts, a PathLine disk ($325 from Aries) holds 4 years' worth of data. Other of the firm's offerings include 8 previous years of PathLine ($495), 5 years of CANCERLIT ($695), and all of the pertinent abstracts on AIDSLINE ($245) since 1980. Databases are updated monthly, quarterly, semiannually, or annually.

* Relevance filter. The main advantage of the Aries system is that it ranks and offers the retrieved abstracts in probable order of applicability using a proprietary relevance filter. That way, if 100 abstracts "drop out" in the search, you may have to read through only the first 10 or 20 to get your questions answered. That's a lot more efficient than getting the abstracts in chronological or alphabetical order by author and then having to wade through all the chaff to find a few kernels of wheat.