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Ada was originally targeted at embedded and real-time systems, and is still commonly used for those purposes. The Ada 95 revision (designed by Tucker Taft of Intermetrics between 1992 and 1995) improved support for systems, numerical, and financial programming.
Notable features of Ada include strong typing, run-time checking, parallel processing, exception handling, and generics. Ada 95 added support for object-oriented programming, including dynamic dispatch.
Ada implementations do not typically use garbage collectionIn computing, garbage collection is a system of automatic memory management which seeks to reclaim memory used by objects which will never be referenced in the future. It is commonly abbreviated as GC. The part of a system which performs garbage collectio for storage management as it is only an optional feature of the language. Ada supports a limited form of region-based storage management , which allows some cases of access to unallocated memory to be detected at compile time.
Ada supports run-time checks in order to protect against access to unallocated memory, buffer overflowIn computer programming, a buffer overflow is an anomalous condition where a program somehow writes data beyond the allocated end of a buffer in memory. Buffer overflows usually arise as a consequence of a bug, and are a commonly exploited computer securi errors, off by one errors, and other avoidable bugs. These checks can be disabled in the interest of efficiency. It also includes facilities to help program verification. For these reasons, it is very widely used in critical systems like avionicsThe onboard electronics used for piloting an aircraft are called avionics . Avionics include communications and navigation systems, autopilots, and electronic flight management systems (FMS). Onboard electronics that are unrelated to piloting tasks, such, weapons and spacecraft.
It also supports a large number of compile-time checks to help avoid bugs that would not be detectable until run-time in some other languages or would require explicit checks to be added to the source code.
The Ada language definition is unusual among International Organization for Standardization standards in that it is free contentFree content works are those other than software which are licensed freely in the same (freedom) sense as Free software is licensed freely. That is to say, recipients are given permission to use the content for any purpose, copy it, modify it, and to redi. One result of this is that the standard document (known as the Reference Manual or RM) is the usual reference Ada programmers resort to for technical details, in the same way as a particular standard textbook serves other programming languages.
In the 1970s, the US Department of DefenseThe United States Department of Defense abbreviated DoD or DOD and sometimes called the Defense Department is a civilian Cabinet organization of the United States government. The Department of Defense controls the U. military and is headquartered at The P was concerned by the number of different programming languages being used for its projects, some of which were proprietary and/or obsolete. In 1975Events January January 1 Watergate scandal: John N. Mitchell, H. Haldeman, John D. Ehrlichman are found guilty of the Watergate cover-up and are sentenced to 30 months to 8 years in jail on February 21 January 5 The Tasman Bridge in Tasmania, Australia, i the Higher Order Language Working Group (HOLWG) was formed with the intent of reducing this number by finding or creating a programming language generally suitable for the department's requirements; the result was Ada. The total number of high-level programming languages in use for such projects fell from over 450 in 1983 to 37 by 1996.
The working group created a series of language requirements documents - the Strawman , Tinman, and Ironman (and later Steelman) documents. Many existing languages were formally reviewed, but the team concluded in 1977 that no existing language met the specifications.
Requests for proposals for a new programming language were issued and four contractors were hired to develop their proposals under the names of Red (Intermetrics), Green (Cii Honeywell Bull), Blue (SofTEch), and Yellow (SRI International). In May of 1979, the Green proposal, designed by Jean Ichbiah at Cii Honeywell Bull, was chosen and given the name Ada. This proposal was a successor to the programming language LIS that Ichbiah and his group had developed in the 1970s.
The Military Standard reference manual was approved on December 10, 1980 ( Ada Lovelace's birthday).
The US Department of Defense (DOD) required the use of Ada (the Ada mandate) for every software project where new code was more than 30% of result, though exceptions to this rule were often granted. This requirement was effectively removed in 1997, as the DOD began to embrace Commercial Off The Shelf ( COTS) technology. Similar requirements existed in other North Atlantic Treaty Organization countries.
The language became an ANSI standard in 1983 (ANSI/MIL-STD 1815 ( 1815 is Ada Lovelace's birthyear)), and an ISO standard in 1987 (ISO-8652:1987). This version of the language is commonly known as Ada 83, from the date of its adoption by ANSI.
Ada 95, the joint ISO/ANSI standard (ISO-8652:1995) is the latest standard for Ada. It was accepted in February 1995 (making Ada 95 the first ISO standard object-oriented programming language). To help with the standard revision and future acceptance the US Air Force funded the development of the GNAT Compiler. The GNAT Compiler is part of the GNU Compiler Collection.
Work continues on improving and updating the technical content of the Ada programming language. A Technical Corrigendum to Ada 95 was published in October 2001. Presently, more work is being done to produce an Addendum to Ada 95 expected in 2005.