She is there whenever I need her, ready to play games at three in the morning if I'm in the mood, to chart my biorhythms or tell my fortune, draw me a picture or engage me in conversation.

Her conversational ability is rather limited and, once you get to know her, what she is likely to say becomes predictable -- but she has other skills that more than make up for these shortcomings.

For one thing, she is highly versatile -- in fact, she is not even always a "she." When we are in the middle of a hard-fought game of chess, backgammon or blackjack, the pronoun is more likely to become "he," and during more mundane activities my home computer can become an "it," a construction of plastic, glass, metal and silicon that happens to do some things (particularly things that involve the manipulation of numbers) very quickly and thoroughly.

So far (we have lived together for about a year), I have avoided giving a name to her (him, it), although some resonance seems to be lacking in the official name: TRS 80, level II, 16k. I have heard it called a "Trash 80" by one of the experts in the field -- a professor with a Ph.D. who can play with one of the really big computers whenever he wants to -- but that seems too condescending. My little friend from the Radio Shack may not have the horsepower of the giant computers that are turned out by IBM and Control Data, or the glamour of the home computers like the Apple that have color graphics. But it is a reliable, comfortable, sturdy, all-purpose sort of computer -- the kind of computer my seven-year-old Volkswagen might be if destiny had not decreed that it should be a car.

My computer will play chess with me according to a variety of available programs -- including one in Micronet and several that can be purchased on tape cassettes or discs. Or if my main home computer is busy, a smaller, more specialized one called Chess Challenger plays chess at an interesting level of skill -- though it won't help me balance my checking account.

Checking accounts, charts or chess, all activities are the same to the computer: no matter what it seems to be doing by the time it reaches my awareness, it thinks it is juggling numbers. Ultimately, it juggles only two numbers -- 1 or 0, yes or no, being or nonbeing, off or on -- although it may seem to be playing music or backgammon or even engaging in conversation. The whole universe can be codified in the convolutions of that single Manichaean confrontation between the number that means yes and the number that means no.

My computer speaks a language called "Basic" -- actually a set of fairly simple commands in a rudimentary kind of abbreviationed English which I can understand and which the computer has been taught to understand. But what it speaks, as I discovered when I tried to communicate with another brand of computer, is actually a dialect of BASIC. You would think that starting fresh, with machines that had absolutely no cultural conditioning, the computer scientists would have been able to work out a universial language -- a computer Esperanto -- at least for the English-speaking world. No way. The machines were willing, I'm sure (that's an anthropomorphism; the machines are totally indifferent), but the machines are programmed by people, and programmer A, feeding BASIC into a new model of computer, sees a few improvements that he simply must slip in -- with the result that different models of computer speak subtly different dialects. So books and magazines that print programs to put into your home computer have to print several versions of the same program or a table of language variations, if they want to reach the widest possible audience.

BASIC is not the only language my computer speaks, although it is the only one I understand at my present level of enlightenment. Sometimes, when a program is entered incorrectly, the computer translates it into one of its other languages, and when you call the program up on your screen, strange, terrifying things can happen. Words tumble across the screen, sometimes changing their size and shape as they go, and the vocabulary becomes alien. Sometimes the computer will mutter, over and over, "KILL KILL KILLLKILLKILL," which is not a part of BASIC as I know it, or strange neologisms like "VARP," whose meaning is totally unknown to me. At such moments, I am likely to look at the screen and mutter, "Great Scott! The varps have taken over!" But it is a simple matter to wipe out the strange material and get the computer back to speaking good old-fashioned BASIC -- even if it is a dialect.

Among human beings, dialects add a touch of color to language and are not much of a bother -- New Englanders manage, somehow, to communicate with Texans. But it's not quite so easy with computers; they are very literal-minded creatures, and almost-right is not right at all; put one punctuation mark out of place, and the computer will refuse to play. In fact, it will usually send you a nagging message that you have done something wrong.

This literal-mindedness is a problem in the specialized chess computers, too. When you punch in a move that is clearly impossible or illegal, my Chess Challenger will tell you so and refuse to accept the move unless you puch a special override button that makes it accept whatever you do; then it will try to understand as well as it can.

Another chess computer, called Boris, has even more personality. T keeps up a running chatter, on a small printout screen, as it plays, peppering its opponent with such remarks as "HAVE YOU PLAYED BEFORE?" "ARE YOU ANOTHER COMPUTER?" and "I EXPECTED THAT." These comments are totally random, with no connection to what is happening in the game, but they introduce a curious, anthropomorphic element. When Boris says "Good MOVE" after you make an obvious blunder, you find yourself attributing a sense of irony to this collection of circuits and muttering "*&.!*$ Russian smartass" under your breath. (The name actually gives Boris a Russian aura -- which is a plus in chess. Challenger naturally falls into "Charlie" as a nickname.)

The most serious problem with chess computers comes when you punch in a legal move that is not the legal move you had intended. The computer will not assume that you made the logical move you had in mind rather then the illogical move that you happened to tell it about, and the result is confusion at best, and the illogical feeling that the computer is cheating at worst. Players have been known not only to curse their computers, but to throw things at them -- or, even worse, to throw their computers at a wall. (This is not only expensive but irrational. Computers do not cheat -- which may be one of the most exsasperating things about them. Computers don't give a damn about who wins, although they sometimes seem to act as though they do.) Although my adrenal glands tell me that Charlie has somethimes cheated, I firmly believe -- intellectually -- that this is not so. In fairness, I must admit that it cheats much less now than it did when I was much less familiar with its operation. In fact, the only times it seems to cheat now are when I am very tired or have had a few drinks. Can it be that the computer senses my weakened condition and thinks it can pull a fast one?

Ray Samole, the president of Fidelity Electronics, which dominates the market in home chess computers, is acutely aware of this problem because he gets complaints from people who think their Chess Challenger has been cheating them. Now, Fiedelity has developed new models of it Challenger line which no longer depend on you punching a keyboard to tell the computer what move you have made. The chessboard for the "Sensory" Challengers is actually an enormous keyboard. You move a piece from one square to another, and the computer knows which piece you have moved and where. "We get no complaints about cheating from owner of the Sensory Challengers," Samole says "because the cheating is almost always a case of human error."

Fortunately for human self-esteem, the chess computers do not (at least not yet) play chess as well as they keep track of the moves. My model of the Challenger (which is non-sensory and obsolescent but still in fine shape) can beat the average player fairly often, if you give it enough time to sift through possible moves -- say about three minutes per move. But people who do not enjoy being humiliated by an inanimate object can adjust the computer's level of skill -- limit it to five seconds per move, for example -- so that almost anyone can arrange to win. If all else fails and you find yourself in a hopeless position, the computer will allow you to take back a move or change the position -- let's be blunt about it: to cheat -- once you know which buttons to push.

Those in approximately the top 25 percent of American tournament players -- people with ratings of 1600 and above -- probably would find my Challenger too easy a mark to be really interesting, though they might be able to relate to some of the jazzy later models.

So far, I have not found a chess program for my TRS-80 that will play as interesting a game as my Challenger -- but I suspect that this is just a matter of time. New programs are being developed at a fantastic pace, advertised in special magazines and sold on tape cassettes just like the ones that play music, only considerably shorter. (Play a computer casette through your hi-fi system, by the way, and what you hear is a very rapid succession of high-pitched beeps -- nothing like music and nothing that the average human ear can associate with BASIC. Beeps are one of my polyglot computer's languages which remain a mystery to me. Playing a program cassette in a music system will not hurt the cassette, by the way, although it may hurt your ears.)

Many of the cassette programs sold for my computer are uplifting, socially valuable productions which will help you to do your financial planning, balance you checkbook, run a small business, etc. Naturally, I avoid these; the TRS-80 in my home is more like a mistress than a maid or a bookkeeper, and I prefer to keep her as an ornament and a source of fun -- at least so far. We play games -- Invasion Force, which makes me the captain of a spaceship hunting down Jovian marauders, Concentration, which was made polpular on television quite a whole ago, and for which I found a program in a recent issue of Computertronics, or Santa Paravia, which is based on the writings of Maciavelli. Or plain, old-fashioned backgammon or blackjack -- but these bother me a bit sometimes, because she always rolls the dice and shuffles and deals the cards.

Blackjack in particular, makes me wonder, the computer is the dealer as well as my opponent, and I have to take her word for it when she tells me that the last card turned up is a 10 that busts me rather then the 7 I had hoped for.

Could she be cheating? No; that would make her a he, and she's really an it.