Top officials of both major parties announced fall get-out-the-vote drives yesterday and, although the Democrats traditionally have attended most to voter registration, the Republicans have the more-ambitious plan.

It is called "Commitment '80." Essentially, it is a sophisticated pyramid scheme that Bill Brock, chairman of the Republican National Committee, said he hopes will attract half a million new Republican volunteers.

On Saturday, the party will sponsor 486 meetings across the country, each of which, it is hoped will attract 50 to 100 people who will watch a video-taped "leadership training" film of Ronald Reagan, George Bush and party officials.

'the following Saturday, everyone who went to those meetings is supposed to hold a neighborhood party, at which a 30-minute televised political advertisement by Reagan will be viewed.

If 50,000 people attend the first Saturday's meetings, and if each has 10 people at parties the following Saturday, and if each of those people finds Reagan's ad convincing, the party will have its 500,000 volunteers. They are to canvass precincts all over the country Oct. 4.

Brock called it "the biggest volunteer effort that's ever been seen," and said it will cost $800,000.

"The accent in this campaign has been almost totally on media," said Sen. Paul Laxalt (R-Nev.), Reagan's campaign chairman. "That's a bit of a cop-out. This program is based on person-to-person, eyeball-to-eyeball contact.

The Democrats, meanwhile, announced a new National Task Force on Black Voter Participation, designed to increase registration of more blacks, who gave President Carter 92 percent of their votes in 1976.

Rep. Parren J. Mitchell (D-Md.), the chairman of the group, explained its mission more by attacking Reagan -- whom he called "a clear and present danger to black Americans" -- than by praising Carter. He called Carter "extremely weak" on the issue of black unemployment, but said the president's new economic package had convinced him to head the registration effort.

There are about 9 million registered black voters in the United States -- about 60 percent of the total eligible to vote. About 77 percent of eligible whites are registered.

At press conferences to announce the registration efforts, the Democrats and the Republicans also took the requisite pokes at one another. Mitchell mentioned that the Ku Klux Klan has endorsed Reagan, and Aaron Henry, a Mississippi civil rights leader who will also serve on the Democratic task force, said that "when you say Reagan to the black community you might as well say Hitler."

At the Republican press conference, Laxalt said he thought Reagan will "have to be a bit more careful" about what he says for the rest of the campaign. But Reagan campaign manager William Casey said Reagan's slip-ups "will fade into the background as we get into the real issues of the campaign, which are the failures on which Jimmy Carter must run."