After the Government legalized private ownership of gold on Jan. 1, 1975, he jumped in and bought heavily. An ounce was then selling for $185. ''We sold in the range of $780, $790. We did very well. It's easier than the construction business.'' he said.

Eisner The House

The Trumps Built

The Trump Organization - Umbrella for the Trump Family Assets

The Trump Organization - Umbrella for the Trump Family Assets OWNED ENTIRELY BY DONALD TRUMP Trump Enterprises Inc. - Purchaser of investment properties, except the Grand Hyatt Hotel Trump Corporation - Real estate brokerage service for Trump Tower, Trump Plaza and some non-Trump projects, including a condominium in St. Moritz, Switzerland Trump Development Company - Developer of Trump real estate projects Wembly Realty Inc. - Purchaser of Commodore Hotel on East 42d Street in Manhattan for conversion to Grand Hyatt Hotel; restoration company for Grand Central Terminal, and operator of the terminal's tennis courts Park South Company - Owner of Barbizon Plaza hotel and adjacent building at 100 Central Park South; sale reportedly imminent Land Corporation of California - Owner of major California land parcels Gold Company - Buyer and seller of gold (inactive since January 1980) OWNED IN PARTNERSHIP BY DONALD TRUMP Regency-Lexington Partners - Half-owner with the Hyatt Corporation of 1,400-room Grand Hyatt Hotel built on skeleton of Commodore Hotel Trump-Equitable Fifth Avenue Company - Half-owner with the Equitable Life Assurance Society of Trump Tower Seashore Corporation of Atlantic City - Half-owner with Holiday Inn of Harrah's hotel casino, scheduled to open in 1984 Trump Plaza: The East 61st Street Company - Limited partnership in 200-unit cooperative apartment, scheduled for occupancy in 1984; Donald Trump 90 percent, Robert Trump and Louise Sunshine 5 percent each ,OWNED BY THE TRUMP FAMILY Trump Equities Inc. - Owner of shopping centers and 25,000 apartment units in Brooklyn, Queens and Staten Island, and 300-unit senior citizen complex in East Orange, N.J. Trump Management Inc. - Manager of 25,000 Trump-owned apartment units in New York area Trump Construction Company - Builder of original Trump housing units

'HE'S GONEWAY BEYOND ME'

A speck on the horizon is Trump Village in the Coney Island section of Brooklyn, a middle-income residential complex that is Fred C. Trump's most visible monument. It was built in the 60's with Mitchell-Lama financing.

In an office at the rear of 600 Avenue Z, a six-story red brick apartment house that was formerly the headquarters of the Trump Organization, sits its chairman, Fred Trump. He has no intention of moving to Fifth Avenue. ''I don't get involved,'' said the founding father, tall, reddish-haired and dapper at 77. ''As you know, Donald has a competitive spirit and I don't want to compete with him.''

Mr. Trump manages the 25,000 units of housing that constitutes the empire he built, and he boasts about his son, Donald. ''He amazes me. He's gone way beyond me, absolutely.''

Fred Trump was a prodigy. His mother had to sign his checks when he started building in 1923 because he was a minor. The impetus for his large-scale projects came after World War II with Federal financing.

He and his wife, Mary, raised three sons and two daughters in a spacious house in the Jamaica Estates section of Queens.