Pascal have also been used for everything from research projects to PC games and embedded systems. Newer Pascal compilers exist which are widely used. Object Pascal During work on the Lisa, Larry Tesler began corresponding with Wirth on the idea of adding object-oriented extensions to the language, to make Pascal a Multi-paradigm programming language. This led initially to Clascal, introduced in 1983. As the Lisa program faded and was replaced by the Macintosh, a further version was created and named Object Pascal. This was introduced on the Mac in 1985 as part of the MacApp application framework, and became Apple's main development language into the early 1990s. The Object Pascal extensions were added to Turbo Pascal with the release of version 5.5 in 1989. Over the years, Object Pascal became the basis of the Delphi system for Microsoft Windows, which is still used for developing Windows applications, and can cross-compile code to other systems. Free Pascal is an open source, cross-platform alternative with its own graphical IDE called Lazarus. Implementations Early Pascal compilers The first Pascal compiler was designed in Zürich for the CDC 6000 series mainframe computer family. Niklaus Wirth reports that a first attempt to implement it in FORTRAN 66 in 1969 was unsuccessful due to FORTRAN 66's inadequacy to express complex data structures. The second attempt was implemented in a C-like language (Scallop by Max Engeli) and then translated by hand (by R. Schild) to Pascal itself for boot-strapping. It was operational by mid-1970. Many Pascal compilers since have been similarly self-hosting, that is, the compiler is itself written in Pascal, and the compiler is usually capable of recompiling itself when new features are added to the language, or when the compiler is to be ported to a new environment. The GNU Pascal compiler is one notable exception, being written in C. The first successful port of the CDC Pascal compiler to another mainframe was completed by Welsh and Quinn at the Queen's University of Belfast (QUB) in 1972. The target was the International Computers Limited (ICL) 1900 series. This compiler, in turn, was the parent of the Pascal compiler for the Information Computer Systems (ICS) Multum minicomputer. The Multum port was developed – with a view to using Pascal as a systems programming language – by Findlay, Cupples, Cavouras and Davis, working at the Department of Computing Science in Glasgow University. It is thought that Multum