The language Pascal was originally designed by Niklaus Wirth around 1970. It has evolved significantly since that day, with a lot of contributions by the various compiler constructors (Notably: Borland). The basic elements have been kept throughout the years:
The Turbo Pascal and Delphi Pascal compilers introduced various features in the Pascal language, most notably easier string handling and object orientedness. The Free Pascal compiler initially emulated most of Turbo Pascal and later on Delphi. It emulates these compilers in the appropriate mode of the compiler: certain features are available only if the compiler is switched to the appropriate mode. When required for a certain feature, the use of the -M command-line switch or {$MODE } directive will be indicated in the text. More information about the various modes can be found in the user’s manual and the programmer’s manual.