Book

Inside the ZX Spectrum Next: Z80 Assembly, System Concepts, and Practical Programming

Welcome to my book about the ZX Spectrum Next and its programming with Z80 Assembly.

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This book is still in development, so what you see here is a very early and incomplete version.

Copyright © 2025-2026 István Novák

This work is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). You are free to:

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  • Attribution — You must give appropriate credit to István Novák, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.

To view a copy of this license, visit: https://creativecommons.org/licenses/by/4.0/

Dedication

Dad, Mom, without your support, I would not become the proud family man and software engineer I am.

Your son

Table of Contents

Front Matter

Part I — The CPU, Bus, and Memory

  1. Z80N: The Next’s Z80 CPU
  2. Talking to the Hardware: I/O Ports and NextRegs
  3. Memory Architecture: ROM, RAM, Banks, and the MMU

Part II — Time and Events

  1. Interrupts: IM1, IM2, and the Next’s Multi-Source Interrupt System
  2. The CTC: Counter/Timer Circuit
  3. The zxnDMA: Moving Data Without the CPU

Part III — Input

  1. Input Devices: Keyboard, Joysticks, Mouse

Part IV — Video

  1. The ULA Screen and Border
  2. Palettes and Colour on the Next
  3. LoRes Mode
  4. Layer 2: True-Colour Bitmap
  5. The Tilemap
  6. Hardware Sprites
  7. The Copper: Graphics Co-Processor
  8. Compositing, Priorities, and Layer Combinations

Part V — Audio

  1. The Beeper and the Border-Sound Heritage
  2. The AY-3-8912 Family: Three Chips, Nine Channels
  3. DACs and Sample Playback

Part VI — Storage and the Outside World

  1. NextZXOS, esxDOS, and the SD Card
  2. The UART and the ESP WiFi Module
  3. The Real-Time Clock and I²C

Part VII — Putting It All Together

  1. Building a Small Game

Appendices

Machine Types01 Z80n