Turbo Pascal was one of the breakthroughs of the 1980s. It was a PC implementation of the standard Pascal language, which was much used at the time to teach computer science. Pascal was one of the first modern languages to be available on the PC. Later it evolved into an object-oriented version that is still going strong as Delphi.
The compiler has a user front end that mimics the original Turbo Pascal command interface - later it acquired a GUI. If you try it out here, note that not all of the commands have been implemented. To run one of the sample programs use the D command to list the directory and then use the W command to load the file followed by R to run it. Use Ctrl-C to stop it.