index.md

# X65 Book: Preface

The **X65 Microcomputer** is a modern interpretation of classic 8-bit computing, blending the simplicity and hands-on nature of vintage systems with modern enhancements. This book serves as a **comprehensive guide** to both the **hardware architecture** and **software development** of the X65, ensuring that readers gain a deep understanding of its capabilities and how to program it efficiently.

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## About This Book

This book is divided into **two main parts**, each focusing on a crucial aspect of the X65:

### [Part 1: The X65 Microcomputer](part_1.md)

This section covers the **hardware and design philosophy** behind the X65, detailing what makes it unique and how it builds upon the legacy of classic computing. Topics include:

- The **vision and goals** behind the X65 project
- The **65C816 CPU**, its advantages, and how it operates in **native mode from boot-up**
- The **memory model**, including flat 16MB addressing and efficient direct page handling
- The **graphics system**, which uses a **beam-chased display list** instead of a framebuffer
- The **sound system**, built around the custom SGU-1 synthesis chip for rich audio
- **Peripheral support**, expansion options, and system input/output design

By the end of Part 1, readers will have a complete understanding of the **X65’s architecture** and what makes it a powerful yet accessible computing platform.

### [Part 2: Programming the X65 in 65816 Assembly](part_2.md)

The second half of the book is dedicated to **writing software for the X65** using **65816 assembly language**. This section provides a structured learning path, covering everything from the basics of the instruction set to advanced optimization techniques. Topics include:

- An introduction to **65816 assembly syntax and structure**
- Working with **registers, addressing modes, and stack operations**
- Handling **memory efficiently** in a flat 16MB address space
- Programming the **graphics system** using the display list
- Generating **sound with the SGU-1 synthesis chip**
- Interfacing with **peripherals and expansion hardware**
- **Optimizing code** for performance and efficiency

By the end of Part 2, readers will have the knowledge required to **develop software, games, and applications** for the X65, as well as extend its capabilities through custom hardware and expansion modules.

## Who Should Read This Book?

This book is for **retro computing enthusiasts, assembly programmers, and hardware developers** who want to explore the **fundamentals of low-level programming** and **hardware interaction**. Whether you're a seasoned developer looking for a modern take on 8-bit computing or a beginner eager to learn about computer architecture, the X65 provides an **approachable yet powerful** platform to experiment with.

## A Journey into Understandable Computing

In an era of ever-increasing complexity, the X65 is a reminder of a time when **computers were simple, understandable, and empowering**. This book is not just about using the X65 - it's about **rediscovering** the joy of low-level programming, hardware hacking, and direct control over a computer's operation.

With that, let's dive in and explore the world of the X65!