THE INCREDIBLE SHRINKING PC : From notebook-style terminals to pocket-size organizers, computer firms are thinking small.

In the beginning--a whole 12 years ago--there were personal computers. Big and bulky, these machines commanded prime desktop real estate and posed a serious hernia risk to anyone who attempted to move them.

But just like its older electronic sibling, the portable calculator, the personal computer started shrinking. First there were the so-called luggables (luggable if you worked out regularly). Then came laptops.

Now hand-held personal computers are the talk of the industry. No fewer than five companies offer models, ranging from a 15-ounce wallet-size device to one with the heft of a three-ring binder.

These hand-held models are hardly a substitute for the personal computer on your desk. They can’t run spreadsheet programs in the blink of an eye, and they won’t appeal much to full-speed-ahead touch typists. In fact, one wag has dubbed them the “toys of summer.”

Nevertheless, these devices represent a giant step toward a goal that has long inspired PC engineers and enthusiasts alike: a full-powered, carry-everywhere, notebook-style computer, equipped for telecommunications and capable of understanding speech and recognizing handwriting.

“We’re seeing the beginning of what people really want and you’ll be seeing a lot more of it very soon,” says Richard Shaffer, editor of Technologic Computer Letter, a PC market analysis newsletter in New York. “We’re seeing the pieces today of the notebook computer that we’ll be able to buy in five years.”

These devices would be a tremendous boon for business, not only for on-the-go executives and professionals, but for traveling sales and service personnel and factory floor workers, as well. In addition, researchers believe that the devices have the potential, once prices drop, to become as popular a consumer electronics item as the pocket calculator because they will be a blend of a notebook, calendar, telephone and computer terminal.

“A lot of people really believe that someday we’ll use computers just like we use telephones,” says Charles Russell, a product manager for Sharp Electronics in New Jersey.

Indeed, early market research suggests that at least 100,000 of these early notebook-style computers--including some models not yet on store shelves--will be sold this year. By 1991, annual hand-held computer sales could reach 280,000, the equivalent of about 13% of all portable computers sold, according to research reports from Zenith Data Systems, a leading manufacturer of portable PCs.

Researchers believe that interest in the machines will explode once telephone technology is built into them, allowing instantaneous data transmission around the globe. Analysts predict that the power needed to operate a cellular telephone, which now requires six computer chips, will soon be contained on a single piece of silicon, clearing the way for computers with built-in telephones.

The path toward the portable notebook computer is being guided by a vision offered more than two decades ago by Alan Kay, now a research fellow at Apple Computer. Kay named his ultimate personal computer the Dynabook, on the theory that it would be a “personal dynamic medium.”

“What I foresaw was a machine that would act like a window to the rest of the world for its user,” says Kay, who directs computer education research for Apple in a Los Angeles elementary school. “The key was always the communications between the Dynabook and other computers.”

Now that the Dynabook name has been appropriated by several computer makers, some advanced technology researchers have taken to calling their work the quest for “ubiquitous computing.”

“Imagine being able to carry around all your computer needs wherever you go,” says James Gasbarro, a research engineer at Xerox’s Palo Alto Research Center, the high-tech product development and think tank where Kay did his original work. “That’s what we’re all working toward.”

Without a doubt, there’s still a long way to go before “ubiquitous computing” becomes a reality. But recent breakthroughs in miniaturization and other key technologies, such as longer battery life, more compact data storage and more legible screens, have allowed many of the pieces of the puzzle to fall into place.

The result is a spate of new hand-held “almost-PCs,” along with more powerful notebooks and ever-shrinking laptop computers. Spanning a wide range of power and prices, these items provide the best indication yet of the applications awaiting portable computing.

And they have far more power and potential than the basic hand-held electronic terminals that have been used for nearly two decades. Pioneered by MSI Data in Costa Mesa, these terminals were first popularized as inventory-counting devices in supermarkets. Equipped with wands capable of reading bar codes, the devices were used to check supplies on store shelves and enter re-stocking orders.

As the use of bar codes exploded, so did the applications for the devices.

Now, equipped with tiny high-speed printers, these hand-held machines are used by Avis Rent-a-Car parking lot clerks to check in returning rental vehicles and issue receipts. Nurses and hospital aides use the devices to record and monitor patient drug doses. The military uses them to keep track of its vast arsenal of equipment and supplies. And utility meter readers in many communities carry the devices on their rounds of neighborhoods to record the information they collect.

Even police departments have gotten into the act. In Huntington Beach, officers use the terminals to issue tickets and record pertinent data about offending drivers.

The new generation of hand-held devices, equipped with their own microprocessors, can perform a far wider variety of multiple tasks.

Not surprisingly, the hand-held, wallet-sized devices have attracted the most attention.

Atari Corp. in Sunnyvale, Calif., and Japanese companies Casio and Sharp Electronics have unveiled devices that weigh about a pound and can be carried in a woman’s purse or inside a man’s jacket. However, the machines have tiny screens and hard-to-use keyboards and cannot operate traditional PC software programs.

Their manufacturers say they are best used as electronic notebooks, telephone directories, expense report filing systems and for other personal and business organizing tasks, and have priced them accordingly: less than $500.

What do you get for this price? Take, for example, the Wizard, the Sharp Electronics device that has been on the market since October. It offers a basic $300 system with an appointment schedule, calendar, telephone directory, memo pad, calculator and clock. With the addition of a $120 software card, the system can keep track of your expense report. With a $130 software card, it will operate as a dictionary and thesaurus. And with a $99 software card, it will serve as an eight-language translator.

The features and pricing have attracted affluent, trend-setting professionals and gadget freaks who are willing to pay a premium for the equivalent of an electronic FiloFax.

But the “hand-helds” don’t stop at what many consider “executive toys” or “mass-market doodads.”

Later this summer, Poqet Computer in Sunnyvale is scheduled to unveil a one-pound battery-powered machine that will be fully compatible with the standard IBM personal computer. The device boasts a standard, typewriter-style keyboard (albeit quite small), an 80-character by 25-line screen (again, pretty small) and credit card-sized silicon memory cards rather than the traditional magnetic disks. But it all comes at a price: about $2,000.

“This is not an executive’s Christmas present,” says Stav Prodromou, Poqet’s president, who founded the company after spending years in Texas Instruments’ consumer products division and at Mattel Electronics. “This is a business product, a productivity tool.”

Analysts agree--to a point. The keyboard and the screen, they complain, are too small for serious and prolonged work. But, they observe, the device is ideally suited for jotting down notes, entering orders or searching for records, and they predict that the device could catch on among mobile white-collar workers, such as engineers, architects and traveling sales people.

Executives and professionals aren’t the only ones being outfitted with computer notebooks.

Last month, Agilis Corp. in Mountain View, Calif., unveiled a four-pound, notebook-sized system aimed primarily at industrial and public safety workers who need computerized information but do not sit at desks in traditional offices.

The systems, which feature snap-together components, are among the first to offer a built-in radio communication network. The network operates at distances of up to a kilometer outdoors and 100 meters indoors, allowing workers in large factories or industrial yards to communicate and share information. The Agilis systems are also among the first to replace the traditional keyboard with a touch-sensitive screen that allows workers to retrieve information and direct operations.

Agilis executives have targeted airplane maintenance, auto assembly and public safety workers as their primary potential users once the system is released for sale next month. “Just because people don’t work at desks doesn’t mean they don’t need to look up information or communicate with others in their work group,” says a company spokeswoman.

Will the “hand-helds” replace many traditional desktop PCs? Not in the near future, analysts agree.

“My pencil and notebook are still faster and cheaper than any notebook computer that I can envision for the decade,” Shaffer says. Stewart Alsop, editor of a PC newsletter in the Silicon Valley, is even more skeptical. “It will take at least 20 years to pack the 50 pounds of computers I have on my desk into something I can carry around,” he says.

Still, both analysts agree that the day is coming. “We’re just at the beginning now,” Shaffer says. “Stay tuned.”