THE MOST dismal time slot on television is the weeknight period between 7:30 and 8 -- a noisy conglomeration of game shows, travelogues and cheap programming known as "prime-time access."

With low costs and high numbers -- Nielsen figures show that half of America's TV sets are on during access -- that half-hour is a video gold-mine. And if trends continue in the current vein, it's going to get both more monotonous and more profitable.

Industry executives say the coming fall season will feature even less access to the access period. Until recently, most stations "checkerboard" access programs -- that is, aired a different one each day. But now more and more such slots are being filled by "stripping," in which the same program is aired everyweekday.

The reason is simple: It is cheaper to shoot a full week's game-show episodes in one sitting. A week's supply of half-hours can be produced for about $15,000. A high-quality local public affairs program could cost as much as twice that much.

The access marketplace is dominated by network-owned and operated stations. FCC rules permit each network to own five, and they are located in the nation's largest cities. Next year, NBC -- which owns WRC here -- will fill every O-and-O access slot with "Family Feud." (Master of ceremonies Richard Dawson starred on "Hogan's Heros" and is mentioned as a possible successor to Johnny Carson.) This is the first time a network has stripped one access show on all of its O-and-Os.

The new climate has already affected producer Chuck Barris; who last week announced that he has cancelled production of "The Newlywed Game," "The Gong Show," "The $1.98 Beauty Contest," "the Dating Game" and two other programs that were doing well in the ratings, but were only available once or twice a week. Barris' production chief Bud Granoff says that "stripping in prime access has snuffed out all the market for once-a-week programs."

Stripping is only the latest development in a programming rut that has many broadcasters despondent over the quality of their access offerings. "We'd like to be doing better," says one executive. "Greed has taken over," adds another. "The stations get the audience, give them garbage and to hell with responsibility."

"I don't like the game shows," admits a station owner. "I'd like to run something that makes me feel good about myself."

Despite such sentiments -- and despite recent innovations like Group W's "PM Magazine, " seen here on Channel 9 -- little change is in sight. "We have nothing to apologize for," says CBS broadcast group vice president Gene Mater. "We will continue the same general schedule [on O-and-Os]. These programs serve a purpose. After all, people aren't turning away to see something else."

Only ABC now talks of the need forsomething different during acces. "The current schedule is not what we want to be all about," says Roy Polevoy, ABC's vice president of programming for owned stations. "We want to move toward local orientation, talk shows magazine shows, that sort of thing. We are going to try an access magazine once a week sometime this year, then we'll add more show if the audience builds up."

It comes as no surprise that, in the television industry, money talks, But it is somewhat surprising the the access-time wasteland was created by the federal government as a public service.

Ten years ago this spring, the Federal Communications Commision (FCC) passed the Prime Time Access Rule (PTAR), an action hotly debated until 1975, when final FCC action forbade network affiliates from carrying network programs or repeats from 7:30 to 8 monday through Saturday. (It also limited network ownership of programs, which cost them money but had little impace on schedules.)

The FCC envisioned local shows, documentaries and children's specials blossoming amid a garden of weakened networks. PTAR opponents -- particularly networks and their affilites -- expected to lose money.

Both sides were wrong. Subsequent FCC studies network power, decreased local public-affairs programming and helped nearly everyone make more money.

The shortened prime time drove up network rates for commercials. In the meantime, local stations suddenly began to show more commericals because National Association of Broadcaters rules permitted 16 minutes of "non-program material" per hour as opposed to only 9 1/2 minutes during prime time. (These limitations are still in effect.)

"Network affiliates, panicked at having to put programs of their own choosing on the air, have discovered that it's not only fun, it's very profitable," Variety noted at the time.

The PTAR may also have saved ABC. It allowed ABC to drop the really bad shows in its schedules and to use its fewer development dollars in greater concentration," notes former ABC executive Bob Shanks. Alone among the networks, ABC supported the PTAR, and in 1975 announced that the rule had helped it finish in the black for the first time in 10 years.

But it first, there was resistance. After passage of the PTAR in 1970, NBC successfully applied for a Sunday waiver of the rule. ABC did the same for Tuesday. Both were trying to protect their evening of strongest programming. Network requests for waivers soon flooded the FCC, which reopened the entire PTAR question. The result was the final 1975 ruling which formalized the Sunday exception and forbade further waivers.

One beneficiary was "60 Minutes." After fondering for three years at five different time slots, in 1976 it found a home at 7 p.m. on newly exempted Sunday. It went on to become one of the nation's top programs.

Unanticipated economic consequences still arise. Because the PTAR forbids network affiliates to carry repeats in access time, non-network independent stations have started to bid frantically for "All in the Family," "Mary Tyler Moore," "M*a*s*h" and other popular shows which compete well against weak access fare. As a result, "the price per episode of desirable network repeats has gone up at least 10 times in the past five years," a local broadcast executive says.

In Washington -- with channel 5 and 20 in the eighth largest market in the country -- the costs of repeats are second only to San Francisco, Advertising Age reported last month. "Laverne & Shirley" episodes (which can be reaired several times) recently sold here at a cost of $21,090 per thousand homes reached. In the much larger New York market, the cost-per-thousand was $8,550.

In 1971 the broadcast industry feared a mass turn-off when the audience first saw the PTAR cutback in network offerings. But nothing happened. Viewers were hooked, and audience levels remained remarkably constant, as they have every year since.

A 1979 staff report from the FCC's special Network Inquiry notes "the virtually complete lack of specific direct attention to the welfare of television viewers" in formulation of the PTAR. "Proceedings seemed to move along," the report continues, "on the implicit permise that viewers' interests are linked, in some fashion, to the amount of profits earned in the television industry."

"Everything that's happening during the access period makes us look good," says one network official. "It proves that things can be worse without us. It shows what the public will get if we're forced out of the picture."

They have a good point," says Robin French, president of syndication for Norman Lear's TAT productions. "The PTAR may eventually bring the good it was meant to, but it's not possible within current economic constraints."

Others disagree. "Quality is in the eyes of the beholder," counters Leonard Firestone, who distributes "Dating Game" and other access programs. l

"I'd rather do 'Newlywed Game' than 'Dukes of Hazzard' 'Charlie's Angles' or 'Three's Company,'" says Barris Productions' Granoff. "They're more insulting because they're scripted and contrived. We're at least dealing with reality. The network criticism is a bunch of baloney. They're no different."

"Everybody," Granoff says, "has one God in this business and that's the ratings book. If quality programming made money, we'd be right there."

There is no reason, however, for nongame access shows to fail in the ratings. "Consumer By-Line" on NBC's Los Angeles outlet, and "To Life!" on New York's CBS station, have ratings equal to or better than game shows.

Group W's "PM Magazine" is another encouraging example. Basically a "People" magazine of the air, it is a cooperative of shared nation features and local reporting which began as a high-risk experiment on the chain's San Francisco station. Group W requires that each program be at least one-third nonlocal, but station officials attend a four-day "PM-U" to learn how to create the impression that local hosts are involved in everything. l

This fall, over 80 cities are expected to carry magazine-format programs. So far, they have won the ratings race in over 50 percent of the markets in which they appear. And they also attract most of the 18 to 49-year-old viewers highly valued by advertisers. In Washington, "PM Magazine" beats the game shows with a 22 percent audience share -- by loses to M*A*S*H" reruns, which have an impressive 37.

Another promising outgrowth of the access slot is the much-acclaimed "Muppets." "The networks couldn't carry us," says a program spokesman. "If there were no access, there would be no 'Muppets.' But at the same time, our production costs are over $300,000 for a half-hour and stripping may kill us. We produce 24 programs a year now, and if stations demand five a week, we're dead."

A similarly pessimistic view can be found at Time-Life Television. "Quality no longer has much to do with it," says Time-Life syndication chief Bob Peyton. "We can't bet 'em so we're joining 'em." Time-Life now offers "Mitchmatch," a stripped game show which Peyton calls "a cross between "To Tell the Truth' and "The Newlywed Game.'"

Norman Lear's comedy-public affairs program "The Baxters" -- which is broadcast during access time in Washington and five other cities -- is also threatened by the new market. TAT's Robin French says that the show is too expensive to be stripped. But Lear's company is selling "The Sullivans" -- currently Australia's No. 1 program -- for use in access. "We'll strip it five times a week," French says. The program follows an Australian family during World War II. And Leonard Firestone is already marketing another Australian production, "Prisoner: Cell Block H," the story of life in a women's prison. It is now aired in 21 cieties, including an access slot in Minneapolis. ("Prisoner" begins here tomorrow at 11 on Chanel 5.)

Whatever innovatins may arise in access, the bottom line will always be in dollars. One station owner recalls that "a few years ago, we tried a local public-affairs program. It cost a lot of money, and our share of the audience dropped from 15 to 2. So we brought back the game shows." CAPTION: Picture, TV producer Chuck Barris, who last week announced that he has cancelled production of "The Newlywed Game," "The Gong Show," "The $1.98 Beauty Contest," "The Dating Game" and two other programs that were doing well in the ratings.