Almost since the birth of the personal computer, the industry has been searching for so-called "killer applications."

This term refers to a software program so useful that people feel they have to own a personal computer just to use it. Throughout the PC's 20-year history, "killer applications" have popped up now and then to boost sales of computers and software.

The first "irresistible" application was the spreadsheet program. Next came word processing and desktop publishing. Then came computer-aided graphics and design. The "killer app" of the current age that is, the software so useful that people run out and buy a computer so they can experience this particular application is the Internet.

Now we think we've spotted the next "killer application:" Reference ROM. Today's computers, with high-speed color display, stereo sound systems, and the ubiquitous CD-ROM drives, have made it possible for publishers to put huge quantities of reference material not just words, but pictures, graphs, film clips, sound bites, etc. on a small CD-ROM disk.

The small computer on a desktop somewhere in your house can now produce more information on more topics than any paper-and-ink encyclopedia ever printed.

Reference ROMs have several advantages that make them preferable to traditional printed reference books. They are vastly smaller and vastly cheaper. The CD-ROM version of the Encyclopedia Brittanica, for example, costs about $100 and fits in a coat pocket, but has as much information as the $1,500, 30-volume print edition.

Searching for a specific datum in a vast sea of data is also easier and faster on a computer, where electronic indexes do the work for you. For all these reasons, CD-ROM editions now outsell reference works in traditional book form. Microsoft's excellent Encarta a work that exists only on CD-ROM is the world's best selling encyclopedia.

We've recently been browsing happily around in an impressive new Reference ROM: "The Complete National Geographic" (for both Windows and Macintosh computers, from Mindscape, (415)897-9900). The set includes every article, map, picture, and advertisement from every edition of National Geographic magazine since it was founded 108 years ago.

This is not a small or simple program: it has 30 CD-ROM discs in all, and costs nearly $200.

The set comes with a fairly fast search engine, and you can print out maps, pictures, etc., from the magazine to your heart's content. By searching a topic say, earthquakes, volcanos, or the bottom of the sea you can learn how human knowledge has increased and changed over the decades.

You can also search advertisements for a single word or phrase. You can leave electronic "bookmarks" on any page you want to come back to.

We don't like everything Mindscape has done with "National Geographic" and there's one point we completely despise. When you load in the product, you have to sit through a commercial for Kodak before you get to the program itself. This is a horrendous precedent. They charge $200 for the product, and then expect you to sit through ads before you can use it?

The software makes the set harder to use than it ought to be. There's a complicated process where you have to insert and "register" each of the 30 discs before using the search engine. The skimpy online "help" section does a poor job of explaining how to do this.

Further, the reproduction of older issues of the magazine is second-rate. While the pictures are sharp and clear, the text is faded a light gray that is hard to read, both on the screen and on a print-out. You can deal with this on screen by "zooming" in on a page to increase the text size, but there's no way to improve the print-out quality of these older articles.

Despite the shortcomings, this is a perfect example of how the CD-ROM is changing the world of reference. Few families, schools, or even libraries would have the money or the space for all 1,300 issues of this magazine. But as a Reference ROM, the full set is easy to buy and store.

For the time being, Mindscape is only selling "National Geographic" as a complete set. But since the discs come packaged by decade, it seems likely that eventually we will be able to buy, say, the '80s alone for $20 or so. (Let's hope they don't put one of those stupid advertisements in each separate decade.)

T.R. Reid is Rocky Mountain bureau chief of the Washington Post. Brit Hume is managing editor of Fox News in Washington. You can reach them in care of the Washington Post Writers Group, 1150 15th St., Washington D.C. 20071-9200, or you can e-mail T.R. Reid at trreid@ix.netcom.com, or Brit Hume at 72737.357@compuserve.com.

For reprint and licensing requests for this article, CLICK HERE.