It's a marriage made in technology heaven, an inevitable match-up of two of the most powerful tools in modern electronics: portable personal computers and advanced radio communications.

Need to send an electronic message, or search a database, or retrieve a file while you're sitting in an airport departure lounge? Soon you'll simply take a little computer out of your pocket, and with a few taps on a miniature keyboard or even the stroke of a pen, you'll be logged in.

Though some types of wireless computer networks have been in place for years, a flurry of recent developments promise to dramatically expand the scope of the technology. Several companies are now pouring hundreds of millions of dollars into computer communications networks that will work hand-in-hand with a new generation of tiny, lightweight computer devices.

Like many marriages, though, the joining of computers and radio communications is complicated and conflict-ridden. The various networks are not compatible with one another, and it will be impossible to equip computers to work with all of them. Further advances are still needed to make the communications devices smaller and cheaper. And potential customers will have to develop new software if they are to make mobile computer communications a valuable addition to their operations, rather than just a fun gimmick.

"Customers don't buy technology; they buy things that make their lives easier," says Jack W. Blumenstein, president of the Ardis data network, a joint venture of Motorola and International Business Machines.

"As an industry, our biggest challenge is understanding what it takes for the customer to make wireless communications simple and painless."

For certain industries, mobile data networks are not a new concept at all. Ardis, for example, was formed in 1984 as a private data network for IBM field service technicians. Express delivery firms, taxi cab companies and public safety organizations--to name just a few--have long had private radio networks that use specialized terminals to carry message traffic between the field and the home office.

Paging services have also provided data communications for a variety of businesses, though paging is a one-way service and is often limited to very short messages. Some ambitious cellular telephone users have already equipped their phones with cellular modems, allowing them to send and receive computer data.