The three biggest lies in America, 1984 edition: (1) "The check is in the mail." (2) "Of course I'll respect you in the morning." (3) "It was computer error."

Of these three infamous fibs, the worst of the lot, by far, is the third. It's the only one that can never be true.

Sometimes, after all, the check may actually be in the mail. Sometimes -- not often, but sometimes -- there might be some respect the morning after. But if the term is properly used, there can never be any such thing as "computer error."

A fundamental truth that tends to get lost in the glitz and glitter surrounding the microelectronic revolution is that digital devices -- clocks, calculators, computers, etc. -- are nothing more than tools to help people do a job. The pencil is a useful tool; the screwdriver is a useful tool; the computer is a useful tool. Nothing more.

In the remote annals of ancient time, before the computer became ubiquitous -- about five years ago or so -- you might have seen a bank clerk accidently write down your $1,000 deposit as $100. Did anybody then call this "pencil error?" Not on your life. The responsibility belonged to the teller, not the tool. Today, though, if a bank statement cheats you out of $900 that way, you know as well as we do what the clerk is sure to say: "It was computer error." Baloney! The computer is reporting nothing more than what the clerk typed into it.

If Mr. Goodwrench installs a new muffler that falls off as soon as you drive off the lot, would you stand by quietly when the dealership blamed the problem on "screwdriver error?"

Why then, when the bill for that job turns out to be 50 percent too high, do we let the same people get away with the excuse that "It was computer error"?

The most galling case of all is when the computerized cash register in the grocery store rings up your $7.59 case of beer as a $12.95 item. If the innocent buyer points out the mistake, the checker, the bagger, and the manager all converge and offer the familiar explanation: "It was computer error."

It wasn't, of course. That high-tech cash register is really nothing more than an electric eye. The eye reads the Universal Product Code -- that ribbon of black and white lines in a corner of the package -- and then checks the code against a price list stored in memory. If the price list is right, you'll be charged accurately.

Grocery stores update the price list each day -- that is, somebody sits at a keyboard and types in the prices. If the price he types in is too high, there are only two explanations: carelessness or dishonesty. But somehow the nostrum "computer error" is supposed to excuse everything.

One reason we let people hide behind a computer's skirts this way is the common misperception that huge modern computers are "electronic brains" endowed with "artificial intelligence." At some point there might be a machine with intelligence, but none exists today. The smartest computer on earth right now is no more "intelligent" than your average screwdriver. At this point in the development of computers, the only thing any machine can do is what a human has instructed it to do.

Anybody who has tried to write a simple program on a computer -- and if you haven't done so, you ought to give it a try -- is aware of that. The really maddening thing about computers is that they do exactly what you tell them to do. The stupidest typing error you make when entering the program will come back to haunt you -- because the computer is too dumb to correct it. This explains why some of the programs we buy for our personal computers produce "computer errors" that seem utterly ridiculous.

You can get a doozy of a mistake out of many PCs, for example, with this simple program in BASIC: 10 A=.99 20 PRINT A

Given this program, many versions of BASIC -- including the standard version for the IBM-PC -- will print a response such as .9899999 -- close, but wrong.

Is this a certified case of "computer error?" Not at all. The computer did just what the human programmer told it to do. The BASIC program, as written, has a little problem in its rounding-off routine that produces the wrong answer.

The nice thing about the computer revolution we are living in right now is that computers -- once the sole province of governmental and corporate behemoths -- are becoming democratic. Anybody can have one.

Over time, as more people get their hands on computers and learn how they work, we will all understand that the excuse, "It was a computer error," is always a fib.