VAXELN

This document is the VAXELN Pascal Language Reference Manual, first published by Digital Equipment Corporation in March 1985. It serves as a comprehensive reference guide to the VAXELN Pascal programming language, which is presented as a compatible superset of the ISO DIS 7185 standard Pascal, extended to support concurrent programming.

The manual covers:

1. Language Fundamentals: Detailed explanations of lexical elements, program structure (compilation units, modules, program and routine blocks, scope of declarations), a wide range of data types (including ordinal, floating-point, strings, arrays, records, pointers, files, and specialized system types like PROCESS, AREA, EVENT, SEMAPHORE, MESSAGE, PORT, NAME, and DEVICE), constant declarations, variable definitions, and the syntax and operation of expressions and Pascal statements (e.g., assignment, conditional, loop, WITH, GOTO).
2. Routines: In-depth coverage of procedures and functions, their declarations, parameter passing mechanisms (including VAR, value, procedural, conformant, optional, and list parameters), function results, calling conventions, and a catalog of VAXELN-specific built-in routines (arithmetic, ordinal, string, type conversion, argument, storage allocation, VAX, and time representation functions).
3. System Programming & Concurrency: Extensive sections on advanced topics such as queues for interprocess communication, subprocesses and synchronization (process blocks, kernel services for events, semaphores, mutexes, user identification codes (UICs), authorization, and program loader utilities), and device drivers and interrupt handling (including IPL procedures and DMA device handling).
4. Input/Output: Comprehensive details on file types (including textfiles), file modes, buffer variables, general I/O procedures (OPEN, CLOSE, GET, READ, RESET, PUT, REWRITE, WRITE), and file, disk, and tape utility procedures.
5. Error Handling & Development: Information on compiler error detection, run-time exceptions, exception handling procedures, and program development aspects like the EPASCAL command, module management, and consistency checking.

The manual is intended for programmers and students with existing knowledge of Pascal, VAX/VMS, and VAXELN.