As if things weren't tough enough in the microcomputer business already, a new set of players may soon be joining the fray trade associations. Such, at any rate, is the prospect raised by the recent announcement that a for-profit subsidiary of the American Society of Interior Designers (ASID) has begun marketing its own customized computer system for designers and architects.

The subsidiary, called ASID Computer Systems Inc., is the brainchild of Joseph F. Indinemao, formerly an accountant with the firm of Laventhol & Horwath. In 1977, Indinemao -- then comptroller of ASID -- approached the society with his idea of forming a company that would provide computer services to ASID and its 22,000 members. In addition, the company would develop a microcomputer system tailored for interior designers and architects, one that could eventually be sold to members and nonmembers alike.

It seemed like a perfect match. The link to the trade association would give the company instant credibility, not to mention a pool of potential customers. As for ASID, the proposed subsidiary offered a way to attract and service members, and perhaps help cover rising expenses as well. Moreover, the organization was willing to try something new. "If I'd suggested starting a computer business to the members of the New York Plumbers Association, they probably would have said, 'No thanks,' " says Indinemao. "I happened to be working with designers, who are creative They said, 'What have we got to lose?"

Now, five years later, ASID Computer Systems has introduced Designwright, a microcomputer system for designers and architects. The bare-bones system, which costs ASID members $9,995, includes microcomputer hardware from various manufacturers and software for word processing and accounting.

For an additional member price of $6,250, a customer can purchase computer-aided design and drafting software that allows a designer to draw three-dimensional floor plans and to move elements around with a special pen pressed against the screen.

The system should be particularly attractive to smaller design companies. "We'd shopped around," says interior designer R. Michael Brown, who runs a $2million-a-year design firm in New York City. He had found that brand-name microcomputer systems did not meet his needs and that customized systems were too expensive. In August, he ordered a $14,000 version of Designwright and offered his firm as one of the dozen sites where ASID Computer will test the system this fall before launching its fullscale sales push.

Other customers have already started to line up. A month after Designwright's unveiling at an industry show in July, ASID Computer Systems had received more than 250 inquiries from people interested in buying the system. Indinemao predicts the company will have no trouble meeting its initial goal of selling 200 systems in 1984. That translates into first-year revenues of $2 million to $3 million, which will more than cover development costs.

Meanwhile, the company continues to grow apace. As of September, ASID Computer Systems was employing some 30 people -- 8 more than ASID itself. "This little corporation has already outgrown its parent," notes Indinemao.

Not that the society should be alarmed. With any luck, after all, it could soon be one of the more prosperous trade associations around.