Comdial Corp., a Charlottesville, Va., designer, manufacturer and distributor of telephone terminal equipment, reported earnings of $3.532 million (24 cents a share) for the first quarter compared with $65,000 (one cent) for the same quarter in 1982. The earnings were a record for the firm.

Sales in the first quarter were $39.569 million compared with $3.11 million a year before.

The huge increases in sales and earnings were primarily the result of the company's acquisition in October of the telephone manufacturing activities of General Dynamics Corp., including telephone manufacturing operations of Stromberg-Carlson Manufacturing in Charlottesville and American Telecommunications in California.

Those assets were acquired for $54 million by Comdial, which raised funds by selling stock to Pacific Telecom, which now owns 48 percent of Comdial; by borrowing money, which subsequently was repaid; and by issuing additional shares and converting warrants, according to company officials.

Despite the size of the acquisition, the company has debt of only between $3.5 million and $4 million, which is mortgage money, said L. Paul Harnois, vice president, secretary and chief financial officer for Comdial. Harnois called the acquisition a good deal for Comdial.

The company said each quarter's earnings were adjusted to reflect the acquisition of R and G Communications Inc. on Feb. 28.

Precipitous drops in the movement of coal cut Norfolk Southern Corp.'s first-quarter earnings by 57 percent and revenue by 18 percent, railroad officials said yesterday.

Profits were $55.9 million (89 cents a share) compared with $131.1 million ($2.10) last year. The 1982 figures combine Norfolk and Western with Southern's first-quarter data for comparative purposes, because the two railroads had not yet merged at this time last year.

Revenue at the Norfolk-based transportation company dropped to $735.2 million from $899.9 million in the first quarter of 1982.

"The worldwide economic recession struck hard at our export coal movements during the first quarter," Chairman Robert B. Claytor said yesterday. "Traffic in construction material and automobiles is picking up now . . . we are looking for more normal business levels before the end of the year."

A. H. Robins Co. yesterday reported first-quarter earnings of $15.7 million (65 cents a share) on sales of $137 million, both records for the Richmond pharmaceutical firm.

The net earnings were 39 percent higher than the $11.3 million (45 cents) posted a year ago, and sales were up 29 percent from $108.7 million, Chief Executive Officer E. Claiborne Robins Jr. told stockholders at the annual meeting in Richmond.

The pharmaceutical firm's previous best showing was in the first quarter of 1981, when it chalked up earnings of $13.6 million (54 cents).

Stockholders were told, however, that the first-quarter showing may not indicate how the firm will perform over the full year.

"As you know, our sales and earnings improved considerably following the first quarter of 1982. Thus, our quarterly comparisons during the remainder of 1983 will not be nearly so dramatic," Robins said. "Nonetheless, we expect 1983 to be another outstanding year for the company."

Evaluation Research Corp. posted profits of $297,490 (14 cents a share) in the first quarter compared with $50,343 (4 cents) last year. Revenue nearly doubled to $6.1 million from $3.2 million.

ERC, based in Vienna, is a professional services firm in the fields of engineering, logistics, information, energy and environmental analysis. President Jack E. Aalseth said he expects this year to continue to be strong for ERC because the company has a substantial backlog.