It is COMMONPLACE to mutter that the computer is going to take over our lives. But, at least in the Washington Baltimore area, the computer already is frequently the key that opens the doors to the leisure time pursuits that keep us same and civilized.

What they call in the trade the "hard ticket" is on the way to replacement at a majority of box office windows by a larger, less comfortable-to-the-waller billet that computers like the Capital Centre's can spit out at 350 minutes.

No one knows for sure how many tickets are sold here each year, but the Centre sells about 3 million for sports and entertainment events. Tickets on sell another million and a half for everything from Rostropovich to camp grounds. And when the Kennedy Centre installs an elaborate new computer system on which planning is now well advanced, almost four million more tickets will be added to the computer hopper.

Tickets by computer, as the numbers suggest, have already touched the lives of a broad segment of the population, and the prospect is for much more.

When its's working right, a computer ticket system provided remarkable speed, convenience and selectivity, even long distance. One dubious theatergoer was won over by its possibilities on a Thursday in 1975 when he walked up to the down- town Ticketron outlet on 17th Street and asked for a ticket to "A Chorus Line" in New York. It was a long shot, because the week before the play had had a smash Broadway opening. Within 10 minutes, the computer had produced a single in the middle of the orchestra. And instead of a scalper's fee, there was merely a routine 60-cent service charge.

The computer however, does not always sing so sweet a tune.

Edward Dougherty, Ticketron's area manager, concedes there have been problems since his office opened here in 1969.

"There was the night when we blithely sold 98 duplicate tickets to the opening of Robert Hooks' production of Genet's "The Blacks" at the Eisenhower, with 1,100 seats. The burden always falls on the house manager, but I felt I had to go down and help him out.

"You understand, you are faced with all these People - mostly couples who have hired baby-sisters, dressed up, parked the car, had dinner and now they march down the aisle to find somebody sitting in their seats.

"Fortunately that production wasn't entirely sold out so we moved some of the customers to other locations, but we couldn't get many people paired. Some people were offered seats to the offerings in the Opera House and the Concert Hall. And for the rest we rufunded their money, as well as their service charges and parking fees.

I explained that the Kennedy Centre was entirely blameless. But you can't imagine what it is like to face all those people. It's an experience I'd not like to go through again. I went home and had a drink." Later investigation showed the mixup was human error, not computer error.

The cause of a similar incident at the Eisenhower this Sept. 23 is still unclear.What is clear, however, is that 37 patrons who appeared with tickets for Mary Martin in "Do You Turn Sommersaults?" did not get seats, and it was a run that was by then totally sold out.

Such occurrenced are less common than in the early days of Ticketron, which got off to a rocky start in 1967.

The firm's two most conspicious failures, Schmitt said, were in Norfolk and Atlanta, where repeated breakdown of the machinery at critical times finally led to cancellation of the exclusive franchises that Ticketron had at SCOPE. Norfolk's city-owned sports arena and concert hall complex and at Atlanta's new sports center.

In Norfolk's case the only possible source of a reserve seat ticket was Ticketron's massive computer in Hackferent parts of the country, and the one that feeds East Coast clients. In the early 1970s the computer had a habit of breaking down unpredictably. This was inconvenient enough in Washington, but at least the purchaser had the option of going to a hard ticket box office. In Norfolk though, there were no hard tickets.

John Shaw, who was then the city finance director, recalls that "it tended to go down just before games, when the demand was heviest. The worst experience was in the winter of 1973 when it happened three times in a month for the Virginia Redskins' hockey games.

"By far the worst night was one that we had promoted especially hard . Our 4,000 regulars already had their tickets.But we weren't able to cope with the 3,000 to 4,000 other fans who showed up after the system went down about 6 p.m. The gate opened at 7 p.m. and we had a mob of people on our hands who simply could'nt understand why there were plenty of seats but no tickets.

"Finally, we issued blanks tickets for emergency purposes, with no seat assignments, at reduced ticket prices. Ticketron made up the price difference to the city. But there was nothing they could do about the fans who had simply gone home in disgust.

"That was when we started looking at alternatives." And before long SCOPE had its own computer, which has never broken down, according to Ken Wheeler, the director of conventions and marketing for the city.

Likewise the Capital Centre's computer, now almost of "down time" and is supported by a back-up system would have similar back-up.

One problem that neither has fully solved is mechanical breakdown at Ticketron's 25 remote outlets in town, she went first to the Connectionticut Avenue branch of Discount Records only to be told that their computer was down. The clerk called the Wisconsin Avenue branch across the border in Maryland and was told that they were still selling tickets. But by thetime the fan arrived such was no longer the case. By the 9 p.m. closing time, neither was operating.

She never got to the concert.

Some outlet sources find themselves getting the blame for the computer breakdown when they feel it's not their fault. John Olson, of Record & Tape Ltd., canceled his contract with Ticketron after a year because he felt that repeated breakdowns at his two branched were "offending customers. One man even threatened to jump across the counter when we couldn't answer his question."

Both Ticketron and Capital Centre officials say that terminal failure can come from one of these causes: mechanical breakdown, a switch problem on electrical lines, or human error at the operating end. With Ticketron's base computer for the East performing better and soon to be replaced, Schmitt regards better trainig and service of remote oatlets to be the company's most urgent problem.

The speed of the computers, combined with proliferation of ticket outlets, creates yet another problem for the customer. Certain events sell out extraordinarily fast, particularly pop concerts. Since relatively few young people have the necessary credit card for arrangements like the Kennedy Centre's Instant-Charge, the rush is on to buy tickets to certain events before they are all gone.

Capital Centre box office open at 10 a.m. normally, and on one day in early 1975 the 18,700 seats to a concert of the hard rock group Led Zeppelin, were gone in three hours. Another series of three shows by Crosby, Stills, Nash and Young at roughly that time sold out in 14 hours.

"The computer changes your whole view of getting tickets," says Julie Revner, recalling her days as a high school rock fan. "I kept going around the Beitway to the Centre for may tickets, even though they say you get equal distribution at each outlet. I have gotten up at 5 o'clock in the morning for John Denver, and when I got there, some people had already been there for two days."

The fact that conputerized ticketing is particularly suited for the youth audeience makes it less surprising that 42 per cent of the 30 million tickets sold nationally in the past year by Ticketron went to that age group. Another 30 was for sports events; 28 for touring shows.

One of the most common complaints about Ticketron locally involves the limited services of its 17th Street office. Though Ticketron was once open downtown from 9.30 to 5.30 the hours are now a strictly enforced 11 to 2 catering only to what Dougherty calls "the luncheon crowd." In the summer, the small anteroom tends to be jammed in a line that one letter-writter compared to that of a "prison cafeteria." This is in part because Ticketron handles all tickets for Wolf Trap.

Schmist and Dougherty acknowledge the inconvenience, but argue that selling tickets at the 17th Street establishment is its secondary purpose, its primary one being management of the areas Ticketron outlets. "We keep it open to the Public basically for convenience and image," says Dougherty. "You know, it would be alot cheaper for us to have an office upstairs in the building." Ticketron has closed its Philadephia field office to ticket purchases and Schmitt indicates it may eventually happen here. Individual downtown ticket office are maintained in New York and Chicago.

Another problem that concerns both customers and Ticketron is the variety of the ticket allotments they draw. The Kennedy Centre, for instance, allots only a small fraction of its tickets to Ticketron, mostly for the youth audience. Fewer than 20 tickets to the recent Brahms festival were sold through Ticketron. Ticketron employees are required to inform persons of all obstructed view seats, but even they cannot antimate situations like a recent one in which Orioles' first-base seats said to a Washington family would have been fine but for a TV camera placed in front of them, blocking their view of the pitcher.

Ticketron was one of the first enterprises to realize the potential for computerized ticket brokerage, and its the only one on a national scalel to survive. There were rough times for it finacially as well as mechanically, but the company is now making money as a division of Control Data.

The idea is simple and has been applied in countries fields: Complex detail work previously done manually is in the run, cheaper, more accurrate, and in this case, more convenient for the customer if done by a machine.

A second computer in hackensack serves the Midwest market, centred in Chicago and Milwaukee. Another in Eaglewood. Calif., serves the West Coast. Each has about 300 outlets. The computers are not yet interconnected - allowing a Washingtonian to buy a ticket to, say, the Hearst Castle at San Simeon, Calif. But that is on the way, along with ties to Europe: In about 7 years, Scmitt says one ought to be able, in an instant, to buy a computerized ticket to, say, La Scala from downtown Washington.

Perhaps Ticketron's largest rival will be the one now planned by the Kennedy Center and New York's Schubert theaters, utilizing a single computer and handling an annual volume of 14 million tickets, or roughly half of Ticketron's nationally.

As planned, that system would include such sophisticated features as video display terminals in the shelves of box offices that in a flash would show the customer a diagram indicating all remaining seats. No more taking the salesperson's word.

Also, the computer would feed into the Center's accounting department and handle all mail orders and subscriptions. These are unusually complex at the Center. As an example, here is how the 140,000 hard-sought seats to the present production of "A Chorus Line" were divvied up (in order of priority). Theater Guild subscriptions, 12 per cent; special group purchases, 20 per cent: mail orders, an unprecedented 44 per cent (and even then 1,000) envelopes were returned); special-price tickets for students and the elderly, etc., 4 per cent: general box office, 13 per cent, and 7 per cent for Instant-Charge and agencies like Ticketron.

The Kennedy Center-Schubert arrangement will be in competition with Ticketron, but Schmitt does not anticipate a drop in business.Similar West Coast competition, on a smaller scale, has not dipped into their trade, he says.

But sooner or later another coast-to-coast computer ticket system will come into business, Schmitt believes.

The "hard ticket," however, is not a dinosaur. Computers are economical only in markets with substantial volume. And then, too, as Norfolk's Ken Wheeler puts it, there will always be those who believe "the hard tickets is the way God intended the ticket to be."