Introduction

This book is the manual for AZM, an enhanced assembler for the Z80. It covers the assembler's own facilities: source syntax and symbols, address and constant expressions, data storage, the layout system for records and tables, register contracts for disciplined subroutines, ops for reusable instruction patterns, and the diagnostics and listings the toolchain produces.

The assembler

A plain assembler translates mnemonics to machine code and leaves every convention in the programmer's head. AZM keeps the direct relationship to the machine — what you write is what assembles — and adds the structure that real projects need: named layouts with field offsets and sizes, declared register contracts that the assembler checks at call boundaries, and composable ops that capture instruction patterns without hiding them. The generated listing always shows the exact bytes, so the additions cost nothing in transparency.

The intended reader

We assume you can read Z80 assembly — registers, addressing, flags, the stack. If you are new to the Z80, AZM Book 2 teaches those fundamentals from nothing and is the place to start; this manual will still be here when you return. If you already write Z80 assembly with another assembler, you can move quickly: the early chapters cover familiar ground in AZM's spelling, and the later ones introduce the facilities other assemblers lack.

The book's method

Each chapter takes one facility and works it through examples that assemble. We move from the source format outward: getting started, then syntax and symbols, expressions, data and storage, and from there into AZM's distinctive territory — layouts, register contracts and ops — before closing with diagnostics and output. The appendices hold the complete directive, operator, CLI and built-in function tables, alongside the Z80 machine reference, so the chapters can teach while the tables stay ready for lookup.

The first chapter installs the toolchain and assembles a first program.