Язык программирования CMS-2 для встраиваемых систем ВМС США.

CMS 2 is an embedded systems programming language used by the United States Navy. It was an early attempt to develop a standardized high level computer programming language intended to improve code portability and reusability. CMS 2 was developed primarily for the US Navy’s tactical data systems (NTDS). computers.

CMS 2 was designed to encourage program modularization, permitting independent compilation of portions of a total system. The language is statement oriented. The source is free form and may be arranged for programming convenience. Data types include fixed point, floating point, boolean, character and status. Direct reference to, and manipulation of character and bit strings is permitted. Symbolic machine code may be included, known as direct code.

A CMS 2 program is composed of statements. Statements are made up of symbols separated by delimiters. The categories of symbols include operators, identifiers, and constants. The operators are language primitives assigned by the compiler for specific operations or definitions in a program. Identifiers are unique names assigned by the programmer to data units, program elements and statement labels. Constants are known values that may be numeric, Hollerith strings, status values or Boolean. CMS 2 statements are free form and terminated by a dollar sign. A statement label may be placed at the beginning of a statement for reference purposes. A CMS 2 source program is composed of two basic types of statement. Declarative statements provide basic control information to the compiler and define the structure of the data associated with a particular program. Dynamic statements cause the compiler to generate executable machine instructions (object code). Declarative statements defining the data for a program are grouped into units called data designs. Data designs consist of precise definitions for temporary and permanent data storage areas, input areas, output areas and special data units. The dynamic statements that act on data or perform calculations are grouped into procedures. Data designs and procedures are further grouped to form system elements of a CMS 2 program. The compiler combines system elements into a compile time system. A compile time system may stand alone or be part of a larger program.

Data declarative statements provide the compiler with information about data element definitions. They define the format, structure and order of data elements in a compile time system. The three major kinds of data are switches, variables and aggregates.

Switches provide for the transfer of program control to a specific location in a compile time system. They contain a set of identifiers or switch points to facilitate program transfers and branches. The switch represents a program address of a statement label or procedure name.

A variable is a single piece of data. It may consist of one bit, multiple bits or words. A value may be assigned in the variable definition. Variables may hold a constant or changing value. Data types include integers, fix point, floating point, Hollerith character strings, status or Booleans.

Tables hold ordered sets of identically structured information. The common unit of data in a table is an item. Items may be subdivided into fields, the smallest subdivision of a table. Allowable data types contained in fields include integer, fixed point, floating point, Hollerith character string, status or Boolean. An array is an extension of the table concept. The basic structural unit of an array is an item. Array items contain fields as defined by the programmer.

Dynamic statements specify processing operations and result in executable code generation by the compiler. A dynamic statement consists of an operator followed by a list of operands and additional operators. An operand may be a single name, a constant, a data element reference or an expression.

The Compiler Monitor System 2 (CMS 2) was a system that ran on the UNIVAC CP 642B (AN/USQ 20). The system software included the monitor, compiler, librarian, CP 642 Loader, tape utility and flow charter.

A batch processing operating system that controls execution of CMS 2 components and user jobs run on the CP 642 computer. It provides input/output, software library facilities and debugging tools. Job accounting is also provided.

A compiler for the CS 1 and CMS 2 languages that generates object code for the CP 642, L 304, AN/UYK 7, 1830A and 1218/1219 computers. During the 1970s there were different versions of the CMS 2 compiler, depending on which computer was used to compile the code. Some source code had to be rewritten to work around some functions. And the different versions of CMS 2 had problems with the debugging tools.

An extended CMS 2 compiler, adding language features for the AN/UYK 7 computer. It only generates AN/UYK 7 object code.

A file management system that provides storage and access to source and object code.

Two object code loaders for loading absolute or relocatable object code.

A set of utilities for managing data on magnetic tape.

The flowcharter software processes flowcharter statements in CMS 2 source code and outputs a flowchart to a high speed printer.