2.14 History’s Largest Design Effort: Ada
The Ada language is the result of the most extensive and expensive language
design effort ever undertaken. The following paragraphs briefly describe the
evolution of Ada.2.14.1 Historical Background
The Ada language was developed for the Department of Defense (DoD), so the
state of their computing environment was instrumental in determining its form.
By 1974, over half of the applications of computers in DoD were embedded sys-
tems. An embedded system is one in which the computer hardware is embedded in
the device it controls or for which it provides services. Software costs were rising
rapidly, primarily because of the increasing complexity of systems. More than 450
different programming languages were in use for DoD projects, and none of them
was standardized by DoD. Every defense contractor could define a new and differ-
ent language for every contract.^12 Because of this language proliferation, applica-
tion software was rarely reused. Furthermore, no software development tools were
created (because they are usually language dependent). A great many languages
were in use, but none was actually suitable for embedded systems applications.
For these reasons, in 1974, the Army, Navy, and Air Force each independently
proposed the development of a single high-level language for embedded systems.2.14.2 Design Process
Noting this widespread interest, in January 1975, Malcolm Currie, director of
Defense Research and Engineering, formed the High-Order Language Work-
ing Group (HOLWG), initially headed by Lt. Col. William Whitaker of the
Air Force. The HOLWG had representatives from all of the military services
and liaisons with Great Britain, France, and what was then West Germany. Its
initial charter was to do the following:- Identify the requirements for a new DoD high-level language.
- Evaluate existing languages to determine whether there was a viable
candidate. - Recommend adoption or implementation of a minimal set of programming
languages.
In April 1975, the HOLWG produced the Strawman requirements docu-
ment for the new language (Department of Defense, 1975a). This was distrib-
uted to military branches, federal agencies, selected industrial and university
representatives, and interested parties in Europe.
- This result was largely due to the widespread use of assembly language for embedded sys-
tems, along with the fact that most embedded systems used specialized processors.
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