Z80DevBoard

Z80DevBoard

The Z80DevBoard is an advanced development board for the Z80 microprocessor, based on the RP2040.

This board is meant to be a practical educational tool, to help students learn how the Z80, one of the first CPUs and the foundation of all modern ones, works, and how to develop software for it.

To the Z80 is combined a modern RP2040, a powerful microcontroller designed by Raspberry Pi. It allows easy interaction with the board's components: you can load a program for the Z80 into RAM; or establish a serial connection with the computer to perform live operations, such as reading and writing to RAM.

The most educational components of the board are the LED matrices, which provide real-time visual feedback on the Z80's activity. Thanks to these LEDs, you can see which address of the RAM the Z80 is accessing, the byte it's reading or writing, whether it is answering to a BUSREQ with a BUSACK, and essentially all the operations the Z80 is executing.

The board mounts five buttons: the four on the right allow the student to save a Z80 program to flash, load a custom firmware for the RP2040, reset the Z80, and put the Z80 into a wait state. The button on the left sends a manual clock signal to the Z80, in fact, the board mounts a Z84C00 (the CMOS version of the Z80) specifically to allow it to work even with a manual clock.

The board can be connected to a computer through a USB-C port, which provides both power and data transmission. On the bottom-right of the board, are mounted two pin sockets, to support expansion boards or to be used in more advanced projects that require additional hardware.

For more advanced debugging, when testing custom firmware, the SWD and SWCLK pins of the RP2040 are accessible on the top-right of the board.

Author

The author of the whole project is: Gianluca Rainis - gianluca-rainis on GitHub.

Sponsor

The PCB prototyping for this project is sponsored by PCBWay.

The boards were manufactured with high precision, faithfully following the PCB design down to the smallest details. The silkscreen is crisp and perfectly readable, with no errors or misalignments. The board edges and corner's holes were cut cleanly and accurately. The drill holes match the component footprints exactly, making placement and soldering straightforward. The SMD pads are precise and clean, even for the most challenging footprints, and solder beautifully.

The PCBWay website is intuitive, even for first-time users. Placing an order is simple, and before proceeding to payment the design is reviewed by their technical staff, who catch and communicate any potential manufacturing issues promptly and professionally, avoiding problems before production even begins.

If you are looking for a reliable, high-quality PCB manufacturer for your own projects, PCBWay is highly recommended!

License

Hardware design files (schematics, PCB, BOM):

Licensed under CERN-OHL-S v2.0

Software, firmware and documentation:

Licensed under the MIT License

AI Disclaimer

No AI was used in the conception, design, engineering, or development of this project. Every circuit and every design decision is the original work of the author.

AI tools were used solely as a writing assistant for parts of the documentation, to help refine and organize technical explanations. All content has been reviewed, verified, and edited by the author.

Documentation

The full documentation is available in the docs/ folder.

Development Tools

• PCB Design: KiCad
• Documentation and code: Visual Studio Code

PCB Manufacturing

The Gerber files for PCB manufacturing are available in the gerber/ directory.

Project Structure

Z80DevBoard/
├── customFootprints.pretty/  # Custom footprints
├── docs/                     # The documentation and the guides
├── firmware/                 # The RP2040 firmware
├── gerber/                   # PCB manufacturing files (Gerber format)
├── images/                   # Documentation images and KiCad symbols
├── .gitattributes            # Gitattributes file
├── .gitignore                # Gitignore file
├── gerber.zip                # Zip folder with all the gerber files
├── Z80DevBoard.kicad_pcb     # PCB layout file
├── Z80DevBoard.kicad_pro     # KiCad project file
├── Z80DevBoard.kicad_sch     # Schematic file
├── Z80DevBoard.step          # 3D model
├── BOM.csv                   # Bill Of Materials
├── CHANGELOG.md              # Change log of the project
├── JOURNAL.md                # Journal of the project
├── LICENSE-CERN-OHL-S.md     # CERN-OHL-S License
├── LICENSE-MIT.md            # MIT License
└── README.md                 # This file

Images

Schematic Diagrams

Complete Schematic (A2 format)

Z80 Section

RP2040 Section

PCB Layout

Without Silkscreen

With Silkscreen

3D Renders

Front View

Back View

Technical Details

• Size: 219mm x 108.5mm
• Layers: 4
• Supply Voltage: 5V, 3v3

Components Table

Firmware

Firmware Video Presentation

https://github.com/user-attachments/assets/ee6d8d69-4003-4e21-8f2b-2f08ad0c8d81

Build

From the project root, make sure CMake and the ARM GNU toolchain (arm-none-eabi-gcc) are installed.

If the toolchain is not in your PATH, provide it explicitly with PICO_TOOLCHAIN_PATH:

cmake -S firmware -B firmware/build -DPICO_TOOLCHAIN_PATH=/path/to/arm-gnu-toolchain
cmake --build firmware/build --parallel

If the toolchain is already in your PATH, you can omit PICO_TOOLCHAIN_PATH.

Output file

The file to load in the RP2040's memory after the build is Z80DevBoard.uf2. You can find it in the /firmware/build folder.

You can find more informations about the firmware, including how to write a custom one, in the documentation.