A.B. Computer Systems is beefing up staff and expanding west in an effort to service a surging client base that is responsible for 250 percent revenue growth in the firm's first three quarters.

As part of the company's expansion, ABCS will open an office at 11 Penn Plaza in mid-town Manhattan at the end of January. The office, which will open with two employees, is expected to better enable ABCS to serve its New York City, Westchester and New Jersey customers.

Although Melville will remain the company's headquarters, "in order to get customers from New Jersey, it seems like we have to have an office in the city," ABCS president Ed Avizur said.

Avizur declined to disclose his firm's revenues, but said sales have jumped through the addition of such customers as a Madison Avenue pager distributor for Wal-Mart and other companies.

"If all goes as planned, we will see tremendous growth in terms of revenues and employees in the first quarter of 1999," Avizur said.

The five-employee, Melville-based ABCS was founded by Avizur in Manhasset in 1989. The closely-held company specializes in accounting and manufacturing software for mid-sized businesses.

ABCS resells SBT accounting software and integrations and writes its own software products to integrate with SBT's package.

"We are writing an import module for one customer now," Avizur said.

The add-on will track containers, add costs and provide other features for importers. Requests for the add-on module have already been received from other resellers throughout the country. The company is considering exporting the product to other English-speaking countries.

"We are also looking to add warehouse management software (to our repertoire) by the end of the first quarter," Avizur said.

Currently, the company has between 15 and 20 active clients.

"The last month of the year is very active for us," Avizur said. "We have a couple of prospects. Much of what we will do next year depends on what those prospects will do."

ABCS will hire two or three new employees in the first quarter of 1999 pending the decisions of the company's prospects.