DIAL-MS Assembler Program Description

This document details the DIAL-MS Assembler Program, a bilingual assembler for the PDP-12 computer, developed on July 1, 1970, by Software Services. It integrates an editor and filing system, derived from the basic LINC program LAP6, with an assembly portion based on PDP-8 programs, including PAL-D. Key features of the assembler include the ability to save and load parts of the symbol table, conditional assembly of lines, various listing options (including a "quick list" feature that removes comments and line numbers, replacing tabs with blanks), support for disk or tape listing, and chaining between source files.

The document provides a program overview, a comprehensive loader map detailing memory allocation for its routines (such as symbol search, expression evaluators, I/O, number conversions, and error handling), and an explanation of the pseudo-op processing mechanism. It elaborates on the symbol table organization, describing the structure and encoding of symbol names and types. Numerous subroutines and pseudo-instruction processors are thoroughly described, outlining their functions, inputs, outputs, and affected registers. The operational logic of the assembler, including main assembly passes, expression evaluation, symbol processing, output buffering, and chaining, is visually represented through flowcharts. The document concludes with a loader map for both 4K and 8K memory configurations and a cross-reference listing of all defined symbols.