ByteCradle 6502

The ByteCradle 6502 is a single-board computer (SBC) platform designed for understanding and experimenting with simple operating systems on 8-bit hardware. Built around the WDC 65C02 microprocessor, it provides a hands-on platform for studying system initialization, memory management, device interfacing, and file system handling.

[!NOTE]
The source code for the ByteCradle 6502 operating system for the Mini is found in a separate repository.

📋 Table of Contents

• BYTECRADLE 6502
• Overview
  • Shared Components
• Tier Comparison
• Obtaining PCBs
• Download ROMs
• License
  • Software
  • Hardware
• Contributing
• Acknowledgements

Overview

Both SBCs share a common design philosophy — to provide a straightforward and accessible 65C02 system, while exploring different levels of hardware capability.

Shared Components

• CPU: WDC 65C02
• I/O: WDC 65C51 Asynchronous Communications Interface Adapter (ACIA)

Tier Comparison

This project offers two tiers of single board computers (SBCs), each tailored to different levels of complexity and expandability:

• Tiny SBC (top): A simple, compact design ideal for learning or small embedded projects.
• Mini SBC (bottom): A more capable version with bank switching, SD card storage, and an expansion bus using the 65C22 Versatile Interface Adapter (VIA).

Feature	Tiny SBC	Mini SBC
PCB	Two layer	Four layer
RAM	32 KiB	512 KiB (bank switched)
ROM	32 KiB	512 KiB (bank switched)
Bank Switching	No	Yes - 64 x 8 Kib banks
SD Card Support	No	Yes - Using WDC 65C22 VIA
I/O Interface	WDC 65C51 ACIA	WDC 65C51 ACIA
Expansion Options	Exposes system bus	Exposes system bus and VIA bus

Obtaining PCBs

You can have the ByteCradle PCBs manufactured at any PCB fabrication service of your choice. However, for convenience and ease of ordering, we recommend using PCBWay.

The following links will take you directly to the shared projects on PCBWay, where you can order the boards:

• Order the Mini Board from PCBWay
• Order the Tiny Board from PCBWay

[!NOTE]
These links direct you to the official project pages for the Mini and Tiny Boards on PCBWay.

Download ROMs

Below are the available ROM images for use with the ByteCradle single-board computers. These ROMs can be flashed onto your device depending on the board you are using.

• TinyROM
  A lightweight ROM designed specifically for the Tiny Board. Ideal for minimal setups, testing, or basic 6502 development.

[!IMPORTANT]
Make sure to select the appropriate ROM for your board model. Flashing the incorrect ROM may result in system instability.

License

Software

All software (including ROM code, tools, and firmware) in this repository is licensed under the GNU General Public License v3.0.

This means:

• You are free to use, modify, and share the software.
• If you distribute modified versions, you must also release them under the GPLv3.

Hardware

All hardware design files (schematics, PCB layouts, bills of materials, etc.) are licensed under the CERN Open Hardware License v2 - Weakly Reciprocal (CERN-OHL-W).

This means:

• You may study, modify, manufacture, and distribute the hardware freely.
• If you distribute a modified version, you must share your changes under the same license.

Contributing

Contributions, ideas, and improvements are always welcome. Open an issue or submit a pull request to get involved!

Acknowledgements

We gratefully acknowledge PCBWay for their generous support in sponsoring the prototype PCB manufacturing of the Mini Board. Their assistance helped accelerate the development and testing of the hardware, and we appreciate their commitment to supporting open hardware projects.