Personal-computer fans byte into Apple Orchard and a big array of other magazines catering to them

For Margot Tommervik, the passwords were ''Apple'' and ''Softalk.''

In 1979, Mrs. Tommervik won more than $15,000 on the ''Password'' TV game show. With part of the money, she and her husband bought an Apple personal computer. As they learned to use it, they decided there was a need for a magazine to keep other Apple users informed about their computers and the scores of products that could be attached to them.

Using the rest of their winnings, plus a second mortgage on their house, as well as their previous experience in magazine publishing, the Tommerviks started Softalk, putting out the first issue of the magazine in September 1980. Since then, the Los Angeles-based publication has grown to more than 240 pages and a paid circulation of about 30,000, almost all of it among Apple users or people about to buy an Apple.

Softalk is just one of several independent magazines being published to provide information on a specific line of personal computers and the company that makes them. The magazines contain articles on new developments in the computers as well as the scores of products that can be attached to them, including printers, disk drives, screens, and software, the instructions that tell a computer what to do. They are also full of advertising from many of the manufacturers of that ''peripheral'' equipment.

In addition to Softalk, Apple users can read Apple Orchard or Nibble; IBM Personal Computer users can choose between PC: The Independent Guide to IBM Personal Computers, and Personal Computer Age; while those who prefer Tandy Corporation's Radio Shack computers can decide among 80-U.S., Colorcomputer News , and 80 Microcomputer.

There may be more publications dealing with these three companies and their products. Other magazines are being published about the products of other computer companies. The phenomenon of a magazine being published to ''support'' just one company's products and its peripherals is so new, publishing experts have trouble keeping track of them.

None of these magazines have any official connection with the companies they cover, though they usually carry an advertisement from them. And in at least one case, some of the copy is provided by a computer company official. Tandy's director of computer marketing writes a regular column for 80-U.S., a Tandy spokesman said.

These highly specialized magazines have joined several other publications started in recent years that cover the computer industry in general. These magazines, including Byte, Computer Merchandising, Computer Age, and Personal Computing, do not stick to one manufacturer or supplier. But their concentration on the computer industry - particularly small personal computers - easily puts them in the specialized category.

A magazine focusing on just one company's computers and the products that are used with it ''is really getting pretty definitive,'' said Thomas King, president of the American Business Press, a trade association of business magazine publishers. ''But a lot of money is being spent on them (computers). So if you've got a good idea, and get some technically qualified editors, you should do all right.''

PC is one of the more successful of the computer magazines, with a paid circulation of about 70,000, a figure that the publisher and editor in chief, David Bunnell, expects will be ''well over 100,00 by the end of this year.''

The mechanism for publishing the San Francisco-based PC began about two weeks after IBM announced the introduction of its personal computer last August, Mr. Bunnell said. Before starting PC, he worked for McGraw-Hill's Osborne division, which publishes book-size guides to various computers. The first issue of PC came out last winter. So far, it is a bimonthly, but starting with the August issue the magazine will come out every month, Mr. Bunnell says.

Finding advertisers and story ideas for PC is no problem, he says, since he estimates there are over 700 companies making a variety of products or software that can be used with the IBM Personal Computer. Over 300 of those products are devoted exclusively to the IBM machine, he adds. ''It (the IBM computer) is spawning new companies every week.''

''I've gotten lots of mail from people who bought IBM computers after seeing the magazine,'' Mr. Bunnell added. ''They see there is a lot of equipment to support the computer.''

In September, he will publish a 500-page directory listing more than 3,000 products that are available for attachment or use with the IBM computer.

His magazine, like most of the other company-related computer periodicals, is available where the computers are sold. For IBM, this means Computerland stores, Sears stores that have the IBM computer, and independent retailers. The exception to this is Radio Shack, which has a policy of not selling any non-Tandy publications in its stores.

Even without that support from Radio Shack, 80-U.S. managed to show about a 65 percent growth rate in circulation last year, to more than 30,000, says Don Scarberry, editor of the Tacoma, Wash., monthly, which has been published since 1978. Most of its sales are from newsstands that carry a wide range of computer and technical magazines, he said.

While all these magazines concentrate on one computer company, another takes the idea a step further. Colorcomputer News, published in Muskegon, Mich., has built a circulation of about 25,000 by dealing with just one product of one company: the Radio Shack 6809 color computer, publisher William Sias said.