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Pascal (programming language)

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The Pascal programming language was developed by Niklaus Wirth as a tool for structured programming which would at the same time be simple to process for a compiler. Wirth named the language in honor of Blaise Pascal. He based the language on the Algol programming language. Wirth also developed Modula-2, a language similar to Pascal which also supports object oriented programming.


Implementations


Early approaches (most notably the UCSD system) translated Pascal code into a machine-independent P-code representation. This intermediate code was then interpreted by a program specific to each architecture. As a consequence, only the small interpreter part had to be ported over to many architectures.

In the late 1980s the Pascal community concentrated mainly on the IBM PC platform, driven in large parts by the inexpensive Turbo Pascal compiler by Borland. Many PC hobbyists in search for a structured replacement for BASIC used this product. Turbo Pascal, being available only on one architecture, translated directly to Intel 8088 machine code, making it much faster than interpreted schemes.

During the 1990s compilers that can be re-targeted to different hardware architectures became more prevalent. This allowed for Pascal translation to native machine code that is at the same time easily ported to new hardware.

With Turbo Pacal version 5 Borland added Object Orientation to Pascal forming the Object Pascal dialect. Their main language from 1996 on, Delphi, is in turn based on this.


Several Pascal compilers are available for the use of general public:

  • GNU Pascal Compiler (GPC) is an additional front-end to the GNU Compiler Collection (GCC), and is written in C. Distributed freely under the GNU General Public License.
  • FreePascal is written in Pascal (so that it compile itself), and is aimed at providing a convenient and powerful compiler, able both to compile legacy applications and to be the means of develop new ones. Also distributed freely under the GNU GPL.
  • Turbo Pascal was the dominant Pascal compiler for PCs during the 80s and early 90s, popular both because of its powerful extensions and extremely low compilation times. Currently, older versions of Turbo Pascal (up to 5.5) are available for free download from Borland's site (registration required).
  • Kylix is Borland's newest reiteration of the Pascal branch of their products. It is the descendant of Delphi, with support for the Linux operating system and an improved object library. The compiler and the IDE are available now for non-commercial use. The compiler (but not the library or the IDE) is supposed to become Open Source software some time soon.
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