Zilog Z80 microprocessor emulator

Maintained by: Simon Lightfoot @slightfoot

This is an emulator for the Z80 processor, ported to Dart from JS and is a simple, straightforward instruction interpreter. There is no fancy dynamic recompilation or cycle-accurate emulation. It is developed to serve as a component of a larger system which incorporates a Z80 as its CPU.

The code assumes that the reader is familiar with the Z80 architecture. If you're not, here are some references:

• Z80 instruction set tables
• The official manual
• The Undocumented Z80, Documented

Usage

A simple usage from example/main.dart:

import 'dart:typed_data';

import 'package:z80/z80.dart';

void main() {
  var system = System();
  system.memWrite(0, 1);
  // 0000| $A8 XOR b
  // 0001| $0E LD c, [address]
  // 0002| $07 [address]
  // 0003| $0A LD a, (bc)
  // 0004| $3C inc a
  // 0005| $02 LD (bc), a
  // 0006| $76 HALT
  // 0007| $AA
  system.load(0, [0xA8, 0x0E, 0x07, 0x0A, 0x3C, 0x02, 0x76, 0xAA]);
  print('before ram[7] = ${system.memRead(7).toRadixString(16)}');
  system.run();
  print('after  ram[7] = ${system.memRead(7).toRadixString(16)}');
  //
  // Expected output:
  //
  // before ram[7] = aa
  // after  ram[7] = ab
  //
}

class System implements Z80Core {
  System() {
    _cpu = Z80CPU(this);
    _ram = Uint8ClampedList(32 * 1024); // 32K
  }

  late final Z80CPU _cpu;
  late final Uint8ClampedList _ram;

  void load(int address, List<int> data) {
    _ram.setRange(address, address + data.length, data);
  }

  int run([int cycles = 0]) {
    if (cycles == 0) {
      while (!_cpu.isHalted()) {
        cycles -= _cpu.runInstruction();
      }
    } else {
      while (!_cpu.isHalted() && cycles > 0) {
        cycles -= _cpu.runInstruction();
      }
    }
    return cycles;
  }

  @override
  int memRead(int address) => _ram[address];

  @override
  void memWrite(int address, int value) => _ram[address] = value;

  @override
  int ioRead(int port) => 0;

  @override
  void ioWrite(int port, int value) {}
}

Features and bugs

Please file feature requests and bugs at the issue tracker.

License

This code is copyright Molly Howell, Simon Lightfoot and contributors and is made available under the MIT license. The text of the MIT license can be found in the LICENSE file in this repository.

Ported from: https://github.com/DrGoldfire/Z80.js