Macro Assembly Program

Overview

This manual provides a detailed internal design description of the MACRO assembly program, originally adapted from the MACRO III program for the TX-O computer to run on the PDP-1. The document is labeled as a "Preliminary Draft Description" intended for internal use only at the Digital Equipment Corporation.

Key Sections

• Input Tape Handler: Describes how the program reads from input tape, including buffer management, character stripping, and parity checking.
• Initialization and Title Sequence: Details the procedures for starting or continuing an assembly pass and managing title punching.
• Reset Sequence: Outlines the reset functions for terminators and internal registers.
• Symbol Generator and Processor: Explains how the program handles integers, pseudo-instructions, and user-defined symbols, including the use of binary/logarithmic searches for symbol evaluation.
• Storage and Location Assignments: Covers how storage words are placed and how the location counter is managed.
• Macro-Instruction Facility: Discusses the strongest yet most complex part of the program, including macro definitions, tables, and nested macros.
• Error Alarms and Symbol Package: Describes how diagnostics are handled and how symbols are printed, punched, or restored.
• Appendices: Includes a program listing and an example of macro instruction usage.