The criterion COBOL system

Higher level programming languages provide problem solvers an access to computers without requiring them to become computer experts. In the traditional environment, compilers perform the relatively complex translation from the higher level language statements into the machine instructions. The differences between the complex data structures and operations of languages and typical simple structures of machines makes this a wide chasm to bridge. The mismatch between data and operations of the languages and machines appears clearly when one considers a language such as Cobol, APL, PL/I or Snobol4. In each of these, the fundamental operations and even basic data types do not translate easily because the language design depends on no one machine. The implementor must build mechanisms ranging from full software interpreters to elaborate subroutine libraries to perform the higher level language operations on higher level language data. Despite the costs, the payoffs of using higher level languages make them worthwhile. And with the widespread use of microprogrammable processors as the base of computing systems, designers can realize the once primarily theoretical higher level language machines. 1 An interpreter for the operations of a higher level language, written in firmware rather than software becomes a higher level language machine. The NCR Criterion Cobol System implements an indirect higher level language machine for 1974 ANSI Cobol in a conventional microprogrammed environment, permitting , execution of a single run unit composed of both Cobol and other language modules in a highly efficient manner. The system consists of a microprogrammed hardware processor supporting both conventional and Cobol machine firmware in a multiple virtual machine environment, a multiprogramming virtual resources operating system, a 1974 ANSI Cobol compiler designed to run in a virtual storage environment, the necessary execution time support subsystems and routines, and Cobol symbolic debug and runtime tuning subsystems. The discussion focuses on the characteristics of the system as a Cobol environment and the structure of the Cobol virtual machine, the compiler, and the support subsystems.