Pastel is an extended version of the Pascal programming language, created in c. 1982 for Amber, an operating system for the S-1 supercomputer project at Lawrence Livermore National Laboratory in California. The Pastel compiler was the inspiration for Richard Stallman's GNU C compiler. Pastel was conceived by Jeffrey M. Broughton, then Project Engineer in charge of compilers and operating system software for the S-1 project, because of dissatisfaction with the PL/1 language in which Amber was being implemented. The language was named Pastel ("an off-color Pascal"). Compared with Pascal compilers of that period, Pastel's features included: Improved type definition Parametric types Explicit packing and allocation control Additional parameter passing modes Additional control constructs Set iteration Loop-exit form Return statement Module definition Exception handling General enhancements Conditional boolean operations Constant expressions Variable initialization References 1982 software Pascal (programming language) compilers