What was going on when I was born?

The Army's Chief of Staff says that worldwide American military commitments, including new commitments in Central America, Chad and the Persian Gulf, threaten to stretch the Army and the other armed forces thin. ''Traditionally, we've had a range of contingency needs that probably exceed the force capabilities that we've been able to generate,'' the Chief of Staff, Gen. John A. Wickham Jr., said in a conversation with reporters Monday. ''That probably applies now.'' Forty-three percent of the Army is now deployed abroad, from West Germany to South Korea, with detachments in Honduras, the Sinai Peninsula and elsewhere in Egypt.

Libya was reported to be moving tanks and ground forces toward Chad's northern settlement of Faya-Largeau today, and Western sources said a Government garrison there was under increasing threat. ''The game is over'' for the loyalist forces, a Western intelligence source said, if Libya continues to intensify its efforts to topple the Western-backed Government of Hissen Habre. The Government is waging a civil war against forces of Chad's former leader, Goukouni Oueddei. The Libyan leader, Col. Muammar el-Qaddafi, supports Mr. Goukouni. In Paris, the Defense Ministry announced that at the request of Mr. Habre, it was sending 180 paratroopers to Chad to serve as instructors for Government forces. The announcement stressed that the troops, who are based in the Central African Republic, would be forbidden to take part in direct combat operations.

Applications for home mortgages have trailed off sharply in recent weeks as interest rates have increased. Officials in the construction and lending industries agree that the decline threatens the recovery of the housing market. But beyond that, there is sharp disagreement as to how much harm may result. A few economists believe a small downturn might help stabilize the market in the long run. But most are concerned that a still-fragile recovery may be prematurely choked off.

IN the last five years, Italy has upstaged France as the inspiration for fashionable food trends in the United States. New and expensive restaurants and fancy-food shops, favored by a status-conscious clientele, offer heretofore unknown pasta and risotto variations, cheeses, wild mushrooms, game dishes, olive oils and exotic vinegars that have taken the play away from some France's most esteemed products. It seemed time, therefore, to go to the source and sample these foods, not only to ascertain how well they have traveled but also to find clues to future culinary trends. So for six weeks, from early June to the end of July, I traveled from the southwestern corner of Sicily to Valtellina in the Alps, visiting not only restaurants, but also the great outdoor and indoor markets. After such lengthy, high-caloric research, it is gratifying to report that a number of products, dishes and meals in Italy were indeed wonderful. Tree-ripened fruits, gelati, coffee, breads in bakeries (if not in restaurants), the intrinsic quality of pasta and rice and the freshness of most seafood are still far superior to our own.

Markets Stock prices were mixed at the close after a late rally erased early losses. The Dow Jones industrial average finished up 5.21 points, to 1,168.27, after having been down more than 2 points at 3:30 P.M. On the overall market, however, declines outnumbered advances by 847 to 726. Turnover on the Big Board expanded to 81.4 million shares from 71.5 million shares the day before. (Page D1.) Prices for Treasury notes and bonds rose modestly. Investors were attracted by prices near the lowest levels since last September. (D9.) The dollar was mixed, while gold prices fell $2 an ounce, to $409.50, in New York. (D14.) Grain futures prices fell. (D14.)

Some critics of Reagan Administration policy toward El Salvador say they see very strong analogies between the United States involvement in the guerrilla war here and the American role in Vietnam. Some Administration officials, rejecting that comparison, argue that there are virtually no parallels between the two wars. A visit to the country and interviews here and in Washington indicate that there are, without much doubt, some similarities between the two wars and between the policies pursued and the problems encountered by United States officials in the two conflicts. There are also, without much doubt, some significant differences. Perhaps the most striking analogy between the experiences in Vietnam and El Salvador has little to do with the situations that prevailed on the ground in both countries. Instead, it involves the world view and political instincts of policy makers in Washington.

International In Chad, Libyan tanks and forces were reportedly moving toward the northern settlement of Faya-Largeau and Western sources said a Government garrison there was under increasing threat. ''The game is over'' for the loyalist forces, a Western intelligence source said, if Libya continues to increase its pressure to unseat the Western-backed Government of Hissen Habre. (Page A1, Col. 6.) Guatemala restored civil liberties. In doing so, the new Chief of State, Gen. Oscar Humberto Mejia Victores, said that all people should be able to pursue ''all the activities guaranteed by the law, including political activities.'' A ''state of alarm'' that restricted civil liberties had been imposed June 29 by Gen. Efrain Rios Montt after an attempted coup failed to oust him from power. (A1:5.)

1. Competing With Monty Monty Plays Scrabble is an electronic game that pits Monty - the machine - against one to three players. It operates on four levels of difficulty, starting with beginners, who will be given hints to improve their game. It comes with a basic 12,000-word vocabulary that can be built up to 44,000 with the addition of advanced vocabulary modules. But you still have to keep score with pad and pencil. Ritam makes the game, which is $150 in Bloomingdale's stationery department, on the mezzanine.

A report in the Executive Changes column of Business Day last Wednesday misidentified Bruce C. Hraba. He is president of Amfac Hotels, a subsidiary of Amfac Inc.

Bill Smith tapped out his corncob pipe, clicked on the mechanical sorter and resumed tucking newly laid eggs into polystyrene cartons. ''I'll be the last chicken farmer in the county,'' he said. ''I keep 30,000 chickens for eggs, and that's small. In the nation there are over 60 operations with more than one million birds. Insurance companies, the Japanese, they're into it. They're cutting prices to beat hell. They're breaking the New York State farmer.'' This is the time of year when William T. Smith 2d is a New York State farmer. He is also a State Senator, but now he is back on the farm in this community of 2,500 people after six months in Albany, one of 210 members of the Senate and the Assembly scattered across the state during this season of legislative hiatus.

Acting on a late-night tip, United States agents rushed to Kennedy International Airport Monday night, halted a jet about to depart for Switzerland and seized two steamer trunks that the Government said were packed with documents subpoenaed more than a year ago from a commodity trader, Marc Rich & Company International Ltd. Federal agents sealed the trunks and brought them to the United States Courthouse in lower Manhattan, where they were placed under the protection of United States marshals. Then, at a court hearing yesterday morning, Federal Judge Leonard B. Sand ordered the firm that recently acquired Marc Rich International, Clarendon Ltd., to turn over by noon today subpoenaed documents that have not yet been delivered. Visibly angered, Judge Sand told lawyers for Clarendon: ''Within 24 hours from noon today, every single piece of paper in control of Clarendon from outside the United States is to be sent to the custody of this court. Failure to comply with that will be a violation of this court's order and will bring further actions.''

The possibility that an infant planetary system is circling a nearby star has been raised by new evidence from an orbiting observatory. The Infrared Astronomy Satellite, an orbiting observatory launched last January, has discovered that the star Vega is surrounded by a giant disk or shell of material. The Jet Propulsion Laboratory of the California Institute of Technology described the discovery yesterday as the first direct evidence of solid objects orbiting a star other than the Sun. The sizes of objects within the cloud could be anywhere from that of buckshot to full-fledged planets. According to the Jet Propulsion Laboratory, the objects must be larger than dust grains, which would have been removed from orbit long ago.