Legislation that would shield Maryland residents from recorded telephone sales pitches won overwhelming approval yesterday as the House of Delegates voted 119 to 8 to prohibit the use of computerized dialing machines in the state.

The same measure won approval from the Senate earlier this month, but the senators now must approve two technical amendments added by the House before the measure can be signed into law by Act Gov. Blair Lee III.

The automated "megadial" system would be abolished under this legislation can be programmed to run through, in numerical order, all the phone numbers on a given exchange, before it moves on to the numbers on the next exchange.

Opponents of the legislation, which was proposed by Sen. C. Lawrence Wiser (D-Montgomery), argued that a dialing system operating from across state lines could bombard Maryland residents with as many calls as one operating inside the state - and the out-of-state machine could not be touched by the proposed law.

In any case, Chesapeake & Potomac Telephone Co. lobbyist W. Orville Wright argued at a committee hearing earlier this year, the megadial machines have achieved a 50 percent success rate in some areas - half of the calls made resulted in sales.

Testimony at a committee hearing on banning megadial early in the legislative session indicated that the robot coller also has been used to send commercial greetings and to dun people electronically for unpaid bills.

"You could be swamped with 10,20 or even 30 recorded calls a day," Del. Marilyn Goldwater, (D-Montgomery) predicted at that hearing. "You could lose control of your own telephone in your own home," added Goldwater, who had proposed similar legislation banning megadial.

Although the bill passed by the House prohibits the robot dialing machines in the state, it sets up no penalties for those who violate this law.

House approval yesterday came with no discussion or debate on the issue. The amendments that were added to the bill were designed to insure that pushbutton dialing machines, as well as actual dialing machines, would be covered by the ban.

"It really boggles the mind, the number of junk phone calls one machine can turn out," Goldwater said at the committee hearing.

At a separate hearing, Montgomery Democratic delegate Ida Ruben recounted her own experience with megadial: the robot computer called when she was not at home, so her own recorded telephone answering machine ended up taking the recorded message.

Sen. Wiser, sponsor of the legislation that passed the House yesterday, could not be reached for comment on his bill's apparent success. Wiser had introduced similar legislation during the 1977 General Assembly session. He got it through the Senate, but it died without getting out of the House Environmental Matters committee before the end of the session.