Assembler Pass 1

Introduction:

The Pass 1 of an assembler is responsible for analyzing the source code and preparing essential data structures for translation into machine code. It processes the source program line by line, identifying and defining symbols, literals, and their memory addresses. During this phase, a symbol table is created to store information about labels and variables, while a literal table records any constants found in the program. The location counter (LC) is used to track memory addresses as instructions and data are encountered. Additionally, Pass 1 handles pseudo-operations (assembler directives like START, END, ORIGIN) to manage memory allocation and program structure. However, it does not generate machine code; instead, it produces intermediate code and resolves forward references by marking them for resolution in Pass 2. This phase lays the groundwork for efficient translation during the second pass of the assembler.