ADA---the project: the DoD high order language working group

The Department of Defense (DoD) High Order Language Commonality program began in 1975, with the goal of establishing a single high order computer programming language appropriate for DoD real-time embedded computer systems. A High Order Language Working Group (HOLWG) was chartered to formulate the DoD requirements for High Order Languages, to evaluate existing languages against those requirements, and to implement the minimal set of languages required for DoD use. Other parts of the effort included administrative initiatives toward the eventual goal: specifically, DoD Directive 5000.29, which provided that new defense systems should be programmed in a DoD "approved" and centrally controlled high order language, and DoD Instruction 5000.31, which gave the interim defining list of approved languages. The HOLWG language requirements were widely distributed for comment throughout the military and civil communities worldwide. Each successive version of the requirements, from STRAWMAN through STEELMAN, produced a more refined definition of the proposed language. During the requirement development process, it was determined that the set of requirements generated was both necessary and sufficient for all major DoD applications (and the analogous large commercial applications). Formal evaluations were performed on dozens of existing languages. It was concluded that no existing language could be adopted as a single common high order language for the DoD, but that a single language, meeting essentially all the requirements, was both feasible and desirable. Four contractors were funded to produce competitive prototypes. A first-phase evaluation reduced the designs to two, which were carried to completion. In turn, a single language design was subsequently chosen. Follow-on steps included the test and evaluation of the language, control of the language, and validation of compilers. The production of compilers and a program development and tool environment were to be accomplished separately by the individual Service Components. The general requirements and expectations for the environment and the control of the language were addressed in another iterative series of documents. A language validation capability (the test code suite), and associated facilities, were established to assure compliance to the language definition of compilers using the name "Ada." The name Ada was initially protected by a DoD-owned trademark.