From VSI OpenVMS Wiki
Jump to: navigation, search

C is a programming langage developed by Dennis Ritchie at Bell Labs in early 70s for software running on Unix. VSI C is a standard conforming implementation of the C programming language with VSI extensions. The VSI C compiler runs under the OpenVMS Alpha and I64 Operating Systems and generates optimized and position-independent code.

VSI C is a native-mode language product, and is integrated into the Common Language Environments. All OpenVMS system services are available to programs written in VSI C. VSI C programs can invoke, as functions, modules written in other languages.

VSI C Features

VSI C features include:

  • support for RMS sequential files and associated access methods in addition to stream file-access methods
  • standard-conformance checking, optional code-quality and portability diagnostics, linter features of [SCA|VSI Source Code Analyzer]
  • complete debug and traceback records for use with OpenVMS Debugger
  • IEEE 754 floating-point support
  • support for installing several C versions on the same node
  • separate modes of compulation to support each of the six C dialects (strict ANSI89, strict C99, relaxed ASI, common, Microsoft compatibility mode)\
  • data types for numeric, nonnumeric, and systems programming etc. (for more features, see VSI C for OpenVMS Software Product Description)


A software license is required in order to use the VSI C software product.

  • For Integrity servers, the license is a Concurrent Use license. Version update licenses are not available for the Integrity servers platform. Rights to use future revisions of VSI C are available only through a Support

Agreement or through a new license purchase.

  • For AlphaServer systems, the license to use VSI C is included in the ALPHA-LP license.

See also