As more than 800 journalists concentrated the most sophisticated technology of modern mass communication on the first big media event of the year, eight men met in secrecy here today and provided no details about their deliberations.

The virtual news blackout about the day's two sessions, totaling seven hours, between Secretary of State George P. Shultz and Soviet Foreign Minister Andrei Gromyko and three top aides on either side was in marked contrast to the exercises in public diplomacy that preceded today's meeting.

All that was heard today from Shultz was this two-liner spoken to a television cameraman at a cocktail party following today's sessions: "We have a convention when we go into this room," the secretary said. "He Gromyko goes to the left, and I go to the right."

Gromyko was equally taciturn in public. During the afternoon session, while journalists were inside the conference room for two minutes of picture-taking, a journalist wielding a crane-mounted microphone picked up a question addressed to Gromyko: "Have you got that in your notes?" "Perfectly right," Gromyko said, without providing a hint what the "that" was referring to.

At the reception, the veteran Soviet foreign minister was asked how the talks were proceeding. "No interviews," he said, holding up his right palm. "No fair."

This sort of thing is hardly the stuff of earthshaking international diplomacy between the two nuclear superpowers, but it was just about all the huge press corps -- said to be at world record size for a meeting of two foreign ministers -- had to go on.

Soviet spokesmen and State Department officials would only state the obvious, that the two delegation have held two meetings.

Helping to interpret these sparse tea leaves were the luminaries of the world press, some of them waiting outside the Soviet and American missions in subzero weather as others milled about in the press center and the lobby of the Inter-Continental Hotel here.

Highly visible U.S. television commentators and anchormen such as John Chancellor, Peter Jennings, Dan Rather and Tom Brokaw wandered through the lobby as did some of the experts hired by the networks to help analyze the talks, among them former ambassador to Moscow Malcolm Toon and the director of Harvard's Soviet research center, Marshal Goldman.

The American press contingent in Geneva was by far the largest, including more than 400 persons. By contrast, there are about 20 Soviet correspondents.

The size of U.S. presence is largely due to a decision by the U.S. networks to originate their major news programs from Geneva for the duration of the Shultz-Gromyko meeting. This seems to have contributed substantially to widespread public expectations that the meeting may lead to an easing of tensions and a new dialogue between the superpowers on arms control.

One U.S. source said that when Shultz first heard that the networks were going to anchor their news broadcasts from Geneva, "there was an intake of breath and sharp expression of disapproval."

In their zeal to provide pictorial background for the occasion, the networks asked the city of Geneva to turn on its famous jet d'eau, a fountain on Lake Geneva that normally operates during the summer. City officials reportedly said it could be done for a price, and the networks are paying close to $80 an hour for the contraption. But Robert Vieaux, Swiss chief of protocol, said Geneva also was picking up a part of the tab, by paying for electricity needed to operate the fountain.

The mechanism was frustrated today for some time by subzero weather that arrived from the east with Gromyko. The weather also affected television coverage as at one point during a live broadcast one camera crew's zoom lens froze and failed to close in on its subjects.

The networks have brought a large contingent of journalists, editors, technical personnel and other aides. A CBS source said the entire operation was going to cost the network more than $300,000. Similar figures were cited by other networks.

NBC News apprently led the invasion of Geneva by beginning its preparations for the operation in November, even before the agreement to hold the talks was announced. The network created an elaborate set of offices and studios on the third floor of the Hilton hotel and brought 57 staffers here. In addition, it hired 35 people locally.

Not to be outdone, ABC-TV promptly asked for accommodations at the Hilton, setting up shop on the fourth floor and bringing about 70 staffers.

The inverse proportion of the amount of hard news and the number of journalists in Geneva was apparent as journalists talked to each other for most of the day or interviewed one another. NBC Radio went so far as to interview Chancellor, a member of the NBC-TV staff.

The absence of news has raised questions about the network decision to bring such large staffs to Geneva.

But network spokesman defended the decision by saying that they are frequently accused of superficial coverage and that this time they had decided to provide in-depth coverage of an event that could lead to the resumption of arms control negotiations.