If information is the silver and gold of our data-saturated high-tech era, then the Lexis/Nexis Data Base is the new Fort Knox.

Lexis/Nexis is a vast, labyrinthine collection of facts and figures, tidbits and treatises, opinions and ideas, all stored in a bank of mainframe computers at the Dayton headquarters of Mead Data Central Inc., a corporate entity dedicated to the ambitious proposition that any datum recorded anywhere should be available to anybody with a personal computer.

The assiduous information-gatherers in Dayton feed their mainframes a daily diet consisting of the full text of scores -- no, hundreds -- of publications chronicling just about every form of human endeavor. The data base includes every word of every day's New York Times and Washington Post, for starters, and then branches out to include AP, UPI, Kyodo, Xinhua (New China), and countless other news services.

Lexis/Nexis offers a bewildering range of magazines and professional journals, ranging from People and Sports Illustrated to Genetic Technology News, The Interavia Air Letter, and several of the indispensable Pasha Publications newsletters, including Coal Outlook, Enhanced Recovery Week and Space Business News.

If all that doesn't satisfy your unquenchable thirst for data, the whole Encyclopedia Britannica is tucked away in one corner of the data base, not to mention every 10-K report filed with the Securities and Exchange Commission, every U.S. patent issued since 1975, and every word of every volume of the Federal Register, the Department of State Bulletin and Congressional Quarterly.

There's a collection of medical literature -- from Archives of Otolaryngology to Clinical Laser Monthly -- and an enormous legal library containing, multa inter alia , complete state and federal reports, 25 law reviews, the full Shepard's Citations and the New Zealand Law Reports.

You want to look up a case from the Massachusetts Tax Appeals Board? Call Lexis/Nexis. You need the complete text of a foreign policy debate on the MacNeil/Lehrer News Hour in October of 1984? Lexis/Nexis has it, tucked in there between back copies of Defense/Foreign Affairs Daily and the BBC Summary of World Broadcasts.

Sadly, though, this multifaceted mother lode of data is a Fort Knox in more ways than one. It's an extremely rich repository, but the vault is extremely difficult to penetrate.

The Lexis/Nexis system was created for a carefully designed system of Nexis-specific terminals built solely to connect with those mainframe computers in Dayton. But when Mead discovered that its professional and business customers were buying personal computers like mad, the firm set out to provide a connection between its massive data base and the standard desktop computer.

The easy way to do this would have been to set up a standard "bulletin board" operation accessible through a modem and any run-of-the-mill communications program: Crosstalk, PC-Talk, etc. But Mead decided to market its own access program -- one that I have found exasperatingly slow and cumbersome to use.

Whenever I call Nexis, I have pretty much come to expect making the call three or four times before getting connected. And the stupid software is written such that you have to reload the whole program and start at square one each time it fails to connect.

Once you're hooked in, Lexis/Nexis has some maddening quirks. Even if you know from the first line that appears on the screen that you want to send a new command, Nexis makes you wait for the entire screen to fill before it will stop and ask what you want. (You're paying for this wasted time, of course.)

The system also has an irritating tendency to disconnect in mid-search; then you have to go back to that awful access program again. Mead wrote its subscribers a letter last year saying this disconnection problem had been solved, but I keep running into it. As you might expect, the price of admission to the Fort Knox of data bases is steep. You pay a "connection fee" of $20 per hour, plus a "network fee" of about $10 per hour, plus a separate fee ranging up to $23 for each distinct "search," or information request (fees are considerably lower in non-business hours). The result is that a half-hour visit with Lexis/Nexis can easily cost $100.

Despite these shortcomings, I use this treasure trove every once in a while and find it valuable. But I would use it a great deal more, and give it a much stronger recommendation, if Mead Data Central would hire a few decent programmers and make its Fort Knox of the information age simpler and more reliable for the personal computer user.