Turbo Pascal, also known as Borland Pascal, is a cheap and powerful IDE for the MS-DOS environment. It uses Pascal and from version 5 onwards Object Pascal as its main programming language. The compiler component of Turbo Pascal was based on the Blue Label Pascal compiler originally produced for the NasSys cassette-based operating system of the Nascom microcomputer in 1981 by Anders Hejlsberg. This was first rewritten as the Compass Pascal compiler for the CP/M operating system and then as the Turbo Pascal compiler for the MS-DOS operating system and CP/M. A version of Turbo Pascal was available for the Apple Macintosh from about 1986 but was eventually discontinued around 1992.
When the first version of Turbo Pascal appeared in 1983, the type of IDE which it used was relatively new. On its debut in the American market, Turbo Pascal retailed for $49.99 US. The integrated Pascal compiler also was of very good quality compared to other Pascal products and was affordable above all. The "Turbo" name alluded to its compilation speed.
In the early 1990s, it was used in several universities to teach the fundaments of programming.
It is likely that Microsoft Pascal was dropped because of the competition provided by Turbo Pascal's good quality and low price. Another theory is that Borland made an agreement with Microsoft to drop development of Turbo Basic, a Basic IDE that stems from Turbo Pascal, if Microsoft would stop developing Microsoft Pascal.
Over the years Borland enhanced not only the IDE but also the programming language, since version 5 it contained object oriented programming features. The last version of Turbo Pascal was called Borland Pascal 7 and contained an IDE and compilers for creating DOS, extended DOS and Windows 3.x programs.
By 1995, Borland had dropped Turbo Pascal and replaced it with the RAD environment Delphi, which included the language Object Pascal. The current version of Delphi still supports all the Pascal enhancements of the earlier products including the earlier object model.