Even though portable faxes won't let you send messages to others while you have your foot pressed to the gas pedal, they do have many advantages -- for one, they allow other people to reach you when you're on the road. Even so, the technology is awkward (it requires available phone connections) and relatively expensive (it's routed through cellular networks).

Instead, developer and manufacturer Motorola suggests trying EMBARC, an acronym for Electronic Mail Broadcast to A-Roaming Computers. The new service, which was launched in 112 U.S. markets this past July and is expected to be available worldwide within five years, picks up electronic messages from an office computer and radios them off a satellite into special receivers that are plugged into traveling laptop, notebook, or palmtop computers. The pocket-size receivers store the data -- pricing and scheduling changes, inventory levels, customer credit ratings, and such -- and automatically download it when the recipients turn on their portables.

The one-way message can be dispersed either as text or as binary code to do a mass update of computer files (such as values in a spreadsheet). That way corporate travelers don't have to dial a public carrier to get their E-mail delivered, and the sender saves the high fees charged by radio-modem-signal carriers or cellular-phone connectors for two-way transmissions. Motorola's pitch is that radio E-mail costs significantly less than a 1,500-character broadcast fax (which Motorola estimates at more than $18 for 50 recipients) or overnight hard-copy delivery (more than $400).

The factor that cuts the cost: expenses are fixed no matter how many people the EMBARC message is addressed to. After a onetime $395 equipment charge, information can be scattered to any number of recipients around the country for as little as 93¢. In addition, prepackaged tidbits such as news, weather, and stock prices are available by subscription at $15 a month.

EMBARC is available from Motorola (Paging Products Division, 407-364-2000) for IBM and Macintosh computers. The $395 start-up price includes software and a data receiver. -- Robert A. Mamis