What was going on when I was born?

The number of young people roaming without authorization through some of the nation's most sophisticated computer systems runs into the hundreds and possibly thousands, according to computer crime experts. Further, they say, the number is growing hand-in-hand with the boom in personal computers. These electronic explorations are no longer the province of a few highly skilled computer science experts. The relatively low cost of computer equipment and the existence of electronic bulletin boards that permit the fast, nationwide exchange of information have opened up the pathways to a vast universe of curious young people who often have only a rudimentary knowledge of the field. Many Americans discovered that some young people were tapping into sophisticated systems from home computers in their bedrooms and basements in early August, when it was reported that a half-dozen Milwaukee youths had gained access to about 60 computers, including one at the Memorial Sloan-Kettering Cancer Center in Manhattan and an unclassified one at the nuclear laboratories at Los Alamos, N.M. Many computer enthusiasts scoff at the Milwaukee group.

A Soviet general gave an account today of the incident involving the Korean Air Lines 747 that implied that a Soviet fighter pilot could have confused the airliner with an RC- 135 reconnaissance plane of the kind used by American forces off the Pacific coast of the Soviet Far East. Col. Gen. Semyon F. Romanov, chief of the main headquarters staff of the air-defense forces, said that as the pilot of the Soviet fighter sought to guide the airliner to a Soviet airfield, the 747 ''flew with extinguished lights, and its outlines resemble much those of the American reconnaissance plane RC- 135.'' Tass Quotes Australian Paper It was the second time in 24 hours that a Soviet statement on the incident has hinted that the Soviet action might have resulted from a mistaken identification of the airliner as a United States spy plane. On Saturday, the official press agency Tass quoted an Australian daily, The Sydney Morning Herald, as saying the Korean airliner ''could have been taken in the Soviet Union for a spy plane since in radars it looks like an intelligence plane of the U.S. Air Force.'' Still quoting the Australian paper, Tass said the Korean 747 could also have been confused with ''a U.S. E4B bomber,'' apparently a reference to the E4B aircraft used as an airborne command post by the Strategic Air Command.

News Analysis JERUSALEM, Sept. 4 - In withdrawing from the Shuf Mountains overlooking Beirut, Israel has formally abandoned the most ambitious effort of its war in Lebanon, aimed at ridding the country of Syrian forces and bolstering a stable, pro-Israeli government with the power to police Lebanese territory. In manner and timing, the army's partial pullout, which began Saturday night and continued through today, contradicted some basic elements of the Israeli strategy developed by Ariel Sharon, Defense Minister at the time, when Israel invaded Lebanon in June 1982. Mr. Sharon's expansive goal went far beyond the stated task of clearing the Palestine Liberation Organization from artillery and rocket range of northern Israeli towns and kibbutzim. His broader purpose was to free all of Lebanon from P.L.O. and Syrian troops, to install a tough Christian government that would sign a peace treaty with Israel and to turn secured territory over gradually to that government's armed forces.

Heavy fighting erupted in the mountains overlooking the Lebanese capital today as Christian and Druse militias scrambled for positions evacuated hours earlier by Israeli troops pulling back from the Beirut area. For the entire day and into the evening, the dull thud of artillery resounded throughout the greater Beirut area. Early this evening the police reported that 34 were killed and 25 were wounded in the day's fighting. Military officers and the Beirut state radio said heavy fighting involving artillery, machine guns and tanks broke out in several areas of the mountains east of here, where Christian and Druse villages exist in close and uneasy proximity.

Senior Reagan Administration officials said today that, two hours before shooting down a South Korean airliner off its coast, the Soviet Union spotted a United States reconnaissance plane in the general area and apparently thought that both aircraft were American reconnaissance planes. But White House and State Department officials insisted that whatever initial confusion might have existed, the reconnaissance plane, an RC-135, was 1,000 miles from the scene of the shooting down of the South Korean 747 jetliner. They said the Soviet military had had ample time to discern that the plane they tracked into their airspace was a commercial jetliner. The Administration continued to maintain that there was no way the Russians could have mistaken the identity of the plane at the time they shot it down. Both The Associated Press and United Press International quoted Administration officials as saying that at one stage the reconnaissance plane had come within 75 miles of the Korean airliner.

In some of the heaviest fighting since the start of the three-year-old civil war, rebel forces attacked the third largest city in El Salvador during the night. Guerrilla radio broadcasts said that more than 300 Government soldiers had been killed or wounded in the fighting in the eastern city of San Miguel, which has a population of more than 150,000, and that the rebels had destroyed two bridges, two coffee warehouses and three gasoline stations. The press office of the Salvadoran armed forces said 10 soldiers had been killed and 35 wounded in the battle. There were no reports on guerrilla casualties.

The East German head of state, Erich Honecker, said today that relations betwen East and West Germany were looking brighter. Speaking at the opening of the annual Leipzig Trade Fair, he said: ''Trade in a time of tension provides a firm basis for stable development in the political sphere.

Goukouni Oueddei, the Chadian rebel leader, warned in an interview in northern Chad over the weekend that his forces would attack French troops in Chad if they got in his way. Mr. Goukouni, who was last seen in public on July 30, summoned Western reporters from Tripoli to the northwestern desert oasis of Barda"i, Chad, near the Libyan border on Saturday. The reporters, the first in northern Chad since civil war broke out in July, returned to Tripoli today.

Government security forces believe they have found the bodies of two white farmers kidnapped by insurgents in Matabeleland province in the past year, the national press agency reported today. It quoted Emmerson Munangagwa, Zimbabwe's Security Minister, as saying captured rebels pointed out the bodies, believed to be those of Robert Dyer-Smith and David Belang.

As they climbed down from a truck that had taken them to a distant place, the men inserted ammunition into the breeches of sporting rifles. ''If you want to speak,'' their leader told a visitor, ''speak in whispers. We do not want to advertise our presence.'' Then the men, walking in single file, headed off into bushland of the Luangwa Valley Game Reserve, 250 miles northeast of Lusaka. In the bushland, parched in the dry season of the year, monkeys, zebras and bucks raced by, half-glimpsed through thickets of scrub. The bush in and around the Luangwa game reserve, Zambia's largest, extends for 20,000 square miles. It is home to one of Africa's last herds of rhinoceroses, and it is the job of the men on the patrol to protect the animals.

The superior general of the Jesuits, the Very Rev. Pedro de Arrupe y Gondra, said goodbye today to the society that he has led for more than 18 years, a period in which many Jesuits espoused liberal views on social and religious matters. Father Arrupe took leave from the generalship in a farewell homily for the 220 delegates from all over the world who gathered here on Friday for the general congregation to elect the 75- year-old Spaniard's successor. On Saturday the congregation formally accepted their leader's resignation. Father Arrupe, who was a missionary in Hiroshima when the atomic bomb burst over the city thus became the first general in the 443-year history of the Society of Jesus to resign from the position to which the holder is elected, like the Pope, for life.

Anti-Government protests in Pakistan stretched into their fourth week today and a clash in Sind Province reportedly left 12 people killed.