Zard80

Run your Z80 with only an Arduino Mega or similar.

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Zard80 is simple: Just wire up every pin on your Z80 to an available digital pin on your Arduino (except VCC and GND, obviously!) and you're good to go!

This should work for modern, CMOS-based Z80s - older NMOS chips reportedly don't appreciate being severely under-clocked.

Configuration

Details like Arduino pinout, system memory size, and debug event logging are configurable:

• Edit include/pins.h to remap the pinout.
• Edit include/z80mem.h to change the memory size.
• Edit include/event.h to change debug event logging capacity.

Behaviour

Before starting the Z80, Zard80 will wait for Serial to connect, and print [Zard80] Online to Serial.

Z80 IO Port 0 is mapped to Serial I/O. When reading from port 0, a response of 0xFF indicates that no character is available to be read.

Zard80 will terminate and print debug events whenever:

• The instruction HALT is executed on the Z80 (HALT pin is set to low.)
• An instruction fetch, memory read, or memory write goes beyond the configured memory size.
• An IO Read or Write is made to an unmapped port (i.e., any except for port zero.)

In these scenarios, the reason for termination will be printed, followed by all logged debug events. The bottom-most debug event is typically the one that caused the termination.

Building

Assembling a Z80 Program

The Proper Way

To assemble the Z80 program for Zard80, You will need zasm (http://k1.spdns.de/Develop/Projects/zasm/Distributions/) in your path, as well as the xxd command.

Place your assembly in main.z80 and run assemble-z80.sh (linux/mac/UNIX) or assemble-z80.bat (windows).

On Windows, xxd can be installed via chocolatey. Other platforms should (usually) have xxd available in their package managers.

The Quick One-Off Way

Having trouble? In a pinch, you can also compile your Z80 assembly using asm80.com, and then use this file to C array converter - simply copy the contents of the array up until the point where all that remains is a load of 0x00 (some extra 0s on the end is fine), and paste them over the existing data in src/z80mem.cpp.

Building and Deploying the Arduino Project

This is a PlatformIO-based project. After assembling your Z80 code, use PlatformIO as normal to build and upload to your Arduino.

When running your project outside of PlatformIO, set your serial connection's baud rate to 115200.