B.J. Moore can't type, but he is betting on the health of the electronic-typewriter industry. Moore, the 46-year-old president of San Jose, Calif.-based Systel Computers Inc., thinks his gamble is pretty safe, because his company's sole product has greatly expanded the -- typewriter's usefulness.

The Systel II -- there is no Systel I -- provides in one unit a half-page display screen, word processing software that runs on the popular CP/M operating system, and a disk drive for unlimited document storage. In short, it supplies the word processing components the electronic typewriter lacked. And the add-on unit, at $3,450, is half the price of most word processors being sold. Throw in the cost of the typewriter and it is still a bargain. Says Datapro Research Corp.'s Sharon Olsen: "Until recently everybody thought electronic typewriters were all well and good, but what do you do with that hunk of expensive machinery when you need a word processor?"

Systel first shipped its product in February and now moves more than 1,000 units a month. It has a nationwide network of more than 200 office-machine dealers, increasing at the rate -- about 50 a month; it has moved ito a new 75,000-square-foot facility, and it has jumped from 20 employees in January to more than 150. "We sell everything we produce," says Moore.

In the surnmer of 1981, Systel's financial outlook, Moore concedes, "was not particularly rosy." In fact, it was grim. Systel's first venture into high tech had bombed.

The company was founded in 1980 when Moore, who spent 10 years as president of Biomation Inc., a leading manufacturer of electronic test-and-measurement equipment, teamed up with two other engincer entrcpreneurs, Samuel Schwartz and Dan Hochman. They thought they had a winning idea for a business-oriented microcomputer. Their Report/80 combined in one unit all the elements that other desktop computer manufacturers usuall sold as muodules. But the product cost a hefty $7,500 and never caught on. By August 1981, the fledgling company had losses of $1.5 million. "We knew ww had to do something different," says Moore.

The idea for the Systel II arose when one of the company's directors, an office-machine dealer, asked if there weren't a way to make a word processor out of the electronic typewriter. "It was just a simple question with a very obvious answer," says Moore.

The idea surfaced the first week in August. With the help of an outside designer, an industrial psychologist who chose and conducted focus groups, and office-machine dealers, the company had its system ready by the second week in February.

Moore attributes the system's success so far to the fact that it is easy to use, affordable, attractive, and "friendly." It is also flexible. With the flip of a switch, the typewriter can be used without disturbing any word processing work in progress. And the Systel can be unplugged from one typewriter and plugged into another -- even if the machines are different makes.

It didn't hurt either that, through one of its directors, Systel was able to sign a deal with Olympia U.S.A. that brought more than 7,000 Systel IIs to market as the Olympia EX100.

Nor did it hurt that Systel was the sole contender in the field.

Other companies, such as Eatontown, N.J. -- based Syntrex Inc., market systerns with word processing software, a screen, and storage for the electronic typewriter. But Syntrex's Aquarius I costs $6,390, and includes a typewriter -- in this case an Olivetti branded with Syntrex's own label -- and a single diskette. Although the Aquarius I interfaces with Olivetti and IBM, it clearly does not have the flexibility of Systel, which interfaces with 18 models from nine manufacturers. Syntrex's new low-end electronic typewriter with screen and diskette -- the $4,795 Libra -- doesn't, either.

Recently, however, competitors have sprung up with the same concept as Systel's. The newest is the Van Nuys, Calif. -- based Lexor Corp. Its Lexoriter Series III, set for October, delivery, provides, the company claims, more storage on a single disk than the Systel and allows the user to manipulate more text at a time. And it costs $1,995. Says Dataquest's Clifford Lindsey, "It takes about 6 months to design a Systel, so I figure they'll have 24 competitors in 24 months."

Moore says Systel is ready to compete. He notes that Systel's CP/M operating system makes more than 2,000 software programs available for the unit. And Systel will offer a communications option. Besides, its established market position gives it an edge. Adds Moore: "I think that when prices reductions can be made, we'll be right there among the leaders "