Ada, a new computer language designed to be the programming standard for the Defense Department's weapons systems, will now be offered on Data General and Rolm Corp. computers, the two companies announced Tuesday. The computers are the first commercial machines capable of running the Pentagon's new language. The Defense Department will begin validation tests of the computers for possible purchase next week.

The announcement marks the beginning of the computer industry's efforts to provide Ada machines to the Pentagon as it seeks to standardize its massive weapons systems computer operations around a single language--the instructions used to build computer programs.

In the mid-1970s, the Pentagon realized that its efforts to speed the computerization of its various weapons systems--involving hundreds of separate contractors--had created a hodge-podge of incompatible computer languages. The need to train programmers to use many languages, to assure compatibility among different systems, and other maintenance problems threatened to boost maintenance costs from $8 billion to $30 billion a year by 1990, according to one study.

To replace this software Tower Babel, the Defense Department decided to create a universal language for its "embedded computers," those that are part of larger systems. Embedded computers are found everywhere from missile guidance systems to a tank's "battlefield automated systems" that control its movement and firing.

After issuing a complex set of specifications in 1978, the Pentagon issued several contracts for competitive language designs. A language designed by Honeywell Bull of France was selected after comments from more than 900 companies and organizations in 15 different countries. It was named Ada.

Ada, the computer language, is named for Ada, the Countess of Lovelace, lover and intellectual collaborator with Charles Babbage, the 19th century mathematician who is credited with conceiving the idea of the computer. A daughter of the poet Byron, and an opium addict, Ada was an exceptional mathematician.

Because it is designed to be a standard, Ada programs will be "transportable" from computer to computer and should lessen the burden of software development and maintenance. "What we're trying to do is get a handle on the costs," says Peter Fonash, Army deputy director of the Ada Program Office, "But cost is only half the game. We also want to improve software reliability and reduce the error-rate." Fonash contends that Ada will initially save the Army hundreds of millions of dollars in programming costs, but that savings will ultimately reach billions.

However, there are concerns, privately expressed in the military, that Ada will not necessarily become the lingua franca of weapons systems. At this time, introducing Ada into actual systems is being left up to the individual services. Given that the first Ada computer has not even been validated yet, it is still uncertain how well the new computer language will do in both the Pentagon and its weapons systems.