John Irving, the successful American novelist, appeared at the Coop yesterday afternoon, where he autographed hundreds of copies of his current number-one bestseller, "The Hotel New Hampshire."

The 39-year-old writer chatted with all who patiently waited in the long, winding line at the store as he started off a threeday swing of appearances in the Boston area, the last stop in a brief Eastern publicity tour to promote his fifth book.

Irving has made numerous appearances recently, in print and on television, but yesterday marked his first public return to Cambridge, where he lives when he's not writing and wrestling in Putney, Vt. Irving first received widespread attention for his 1978 bestseller, "The World According to Garp."

Garp Mania

A large crowd warmly welcomed his return, armed not only with fresh copies of his latest book, but also with hard- and soft-cover editions of "Garp," his three other books, and copies of an August issue of Time magazine featuring Irving on the cover.

"A very good friend recommended "Garp to me last summer. So this is as good a time as any to get it along with his new book," John Marcelynas, of Boston, said yesterday while waiting in line.

Others, like Lorie Dillingham, of Boston, bought multiple copies of "The Hotel New Hampshire." "One's for my brother-in-law. Two are for friends. One's for me," she said, adding, "I think he's a fabulous writer."

Irving, wearing a green LaCoste shirt and blue chinos, joked with his fans during the signings. When one man asked if he would sign his worn copy of "Garp," Irving said, "Sure. It's still good, isn't it?"

As Irving dished out signatures, he received a banana, an artist's business card and greetings from several friends.

"Irving's parents are my parents' best friends, because I come from Exeter," Deborah Taft '84 said, adding, "I'm sure I met John when I was a little kid, but I don't remember because he's twice my age."

The Coop yesterday sold approximately 400 copies of Irving's latest work, which has recently been the store's most popular book, selling more than 20 copies per day, George Stephens, the Coop's trade book buyer, said yesterday.

In an interview following his appearance, Irving said that the publicity that he has received has not jeopardized his seriousness as a writer. "I think the greatest jeopardy to your work is not giving it sufficient time. I have much more time to work now than I had when I had to teach for a living," he said.

"I am very pleased that my fiction is popular. But I don't assume that because it's popular that it's not serious," he added.

But Irving said that despite all the media attention surrounding "The Hotel New Hampshire," that work no longer "occupies the center of my imagination." Currently, a very short novel--"the kind that could be read in one sitting"--is in the typewriter, he said.

For two more days, though, "The Hotel New Hampshire" will remain very much on the minds of Irving's Boston-area fans. Last night, he gave a reading at Word-sworth 2. He gives a 7:30 p.m. reading tonight at The Boston Public Library, and he will also make appearances at Barnes & Noble in Boston and the Harvard Bookstore Cafe.

"My audience means a great deal more to me than my reviews." Irving said, adding. "I enjoy the vehicle of public reading very much. It's something I do well and enjoy doing.