Algol, Rt11

This document serves as the DECUS Program Library write-up for "RT-11 ALGOL," a compiler and run-time system for the ALGOL-60 programming language, designed to operate on 16K or larger PDP-11 systems running RT-11 V02B.

The document provides comprehensive technical information on:

• System Components: It details the stack-oriented simulator, memory management (which uses a software virtual memory system for dynamic allocation of program/data segments), and file handling capabilities.
• Operating Instructions: It explains how to compile source code into an ALGOL code file and how to run compiled programs using the run-time system, including command-line options and memory configuration.
• Compiler Details: It outlines the compiler's implementation as a recursive descent system, notes its compatibility with Burroughs B6700 Extended ALGOL, and specifies implemented data structures and control statements.
• Technical Appendices: The majority of the document is comprised of detailed appendices that provide technical specifications for the internal operation of the compiler and run-time system. These include:
  • Simulator Internals: Instruction decoding, opcodes, and addressing modes (R+, C+, F+, F-).
  • System Data Structures: Explanations of Return Control Words (RCWs), Mark Stack Control Words (MKSCWs), file/array/program descriptors, and memory links.
  • Programming Language References: Lists of reserved words, built-in functions, file attributes, and compile-time options.
  • Advanced Features: Specific guidance on using pointers, REPLACE/SCAN statements, and "Picture" constructs for data editing.