To hear the developers of Power Desk tell it, the $99 computer software is the best thing to happen to offices since administrative assistants.

It can store and sort up to 4 million names and addresses, keep track of 13,000 appointments, format letters and envelopes, calculate bills, protect secrets and remind you of Mom's birthday.

Power Desk, which can be used on any IBM personal computer or compatible machine, was developed by Software Studios, a small Annandale company that expects the product to increase its revenue by 300 percent in the coming year.

"We have already sold 3,000 units and site licenses nationally and internationally. That isn't bad for a product that was just introduced last month," said Wade Dowdle, president of Software Studio.

Dowdle's customers include several trade associations, telephone companies, corporations, stock brokers and real estate agents. "We also have a good number of government executives who use the software, and we should be listed on the {General Services Administration} schedule within months," he said.

Why are these organizations buying Power Desk? "Because it integrates the word processor with the data base," Dowdle said. For example, a letter can be composed on the software's word processing program and sent out to all those on a list stored in its data base, all with the touch of two buttons, Dowdle said. Each letter can be personalized with a code key that allows the writer to drop in a name and up to 15 other pieces of information in the middle of the text.

The software also features an encryption program "that is so secure that we cannot unravel the file once it is scrambled," Dowdle said. The program appears illegible to those who do not have the correct password. Power Desk uses a cipher similar to that of the Navy to encrypt the information.

Dowdle has been working on the program for the past five years. In 1982, he left his job as president of a trade association to start a six-person computer company.

"I went on sabbatical from the {association} job and wrote a book on computers," he said. "I got so fascinated with the subject that I decided it was possible to go into the computer business."

Software Studios introduced PC Desk, a predecessor to Power Desk, in 1982. That program has calculator and word processor functions, but no data base or spell-checking feature. About 45,000 of them have been sold.

Now, Dowdle is busy contacting dealers and distributors to get Power Desk into stores and is advertising the product in trade publications that cater to IBM personal computer users. "It should be on the store shelves within the next two months," he said.

Software Studios' next project is a program to tie computer systems together so that a group of computer users can have access to the same data base. "Each system will have access to the other, and all can run on Power Desk at the same time," Dowdle said. "Someone can be updating a file, someone else can be scanning a file and a third person can be writing a letter, all using the same program."

While Dowdle hopes Power Desk will greatly increase Software Studios' sales, he does not plan to increase the size of the company's staff, which still is at six people. "We found that we are able to do this without staff growth," he said. "The most labor-intensive thing we do is sign contracts."