Editing ICL VME (section)

===System Programming Languages: S3 and SFL===

The primary language used for developing both the VME operating system itself and other system software such as compilers and transaction processing monitors is [[S3 (programming language)|S3]]. This is a high level language based in many ways on [[Algol 68]], but with data types and low-level functions and operators aligned closely with the architecture of the 2900 series.

An [[assembly language]] SFL ('''S'''ystem '''F'''unction '''L'''anguage) is also available. This was used for the development of VME/K, whose designers were not confident that a high-level language could give adequate performance, and also for the [[IDMS]] database system on account of its origins as a third-party product. SFL was originally called '''M'''acro '''A'''ssembler '''P'''rogramming '''L'''anguag'''E''' (MAPLE), but as the 2900 architecture was being positioned as consisting of high level language machines the name was changed at the request of ICL Marketing. It had been developed as a part of the toolkit for System D, which was subsequently cancelled. Related families of assemblers for other architectures (CALM-xx running under VME, PALM-xx developed in Pascal and running on various hosts) were developed for internal use.

Neither S3 nor SFL was ever promoted as a commercial development tool for end-user applications, as neither were normally delivered as a standard part of the operating system, nor were they explicitly marketed as products in their own right.  Both SFL and S3 were however available as options to user organisations and third parties who had a specific need for them.