BASIC-PLUS-2

This document serves as the primary language manual for BASIC-PLUS-2, as implemented in July 1977. It covers language syntax, statements, and advanced features for developers using the language on the DECSYSTEM-20 and PDP-11 systems running TOPS-20, RSTS/E, RSX-11M, and IAS operating systems.

Key topics include:

• Program Structure: Guidelines for line formats, character sets, and documentation using REM statements and comment fields.
• Elements of BASIC-PLUS-2: Definitions for constants, variables, arithmetic/logical/relational expressions, array declaration (DIM), and matrix operations.
• I/O Operations: Comprehensive coverage of terminal input/output (INPUT, PRINT, PRINT USING), file handling (OPEN, CLOSE, RESTORE, SCRATCH), and advanced record-oriented I/O for sequential, relative, and indexed files.
• Control Flow: Detailed explanations of conditional and unconditional branching (GOTO, ON-GOTO, IF-THEN-ELSE), loops (FOR, NEXT, WHILE, UNTIL), and subroutines (GOSUB, RETURN, ON-GOSUB, SUB/SUBEND).
• Error Handling: Use of ONERROR, RESUME, and a detailed error table (ERR/ERL/ERN$).
• Functions: Extensive lists of built-in trigonometric, algebraic, and string manipulation functions, as well as instructions for creating user-defined functions (DEF).
• Program Segmentation: Techniques for linking and chaining programs and sharing data via the COMMON statement.
• Appendices: Includes a summary of statements and operators, an ASCII code table, and a glossary of terms.