const operands = []; let operandCount = instruction.operands;
LD A, 01h LD B, 02h LD C, 03h LD D, 04h LD E, 05h Note that this is a highly simplified example and real-world Z80 code can be much more complex.
function getMemoryAddress(binaryData, index) { // ... implement memory address retrieval ... }
return disassembly.join('\n'); }
A disassembler is a program that takes machine code (binary) as input and translates it into assembly language. This process is also known as reverse compilation or decompilation. The goal of a disassembler is to recreate the original assembly code from the binary data, making it easier to understand and analyze.
<!DOCTYPE html> <html> <head> <title>Z80 Disassembler Online</title> <style> body { font-family: monospace; } </style> </head> <body> <h1>Z80 Disassembler Online</h1> <form> <textarea id="input-binary" rows="10" cols="50"></textarea> <button id="disassemble-btn">Disassemble</button> </form> <pre id="output-disassembly"></pre>
while (pc < binaryData.length) { const opcode = binaryData[pc]; const instruction = z80Instructions[opcode]; z80 disassembler online full
for (let i = 0; i < operandCount; i++) { const operandType = instruction.operandTypes[i]; let operandValue;
To use the online disassembler, simply copy and paste the following binary data into the input field:
if (!instruction) { disassembly.push(` Unknown opcode ${opcode} at PC=${pc}`); pc++; continue; } const operands = []; let operandCount = instruction
document.getElementById('disassemble-btn').addEventListener('click', () => { const binaryData = document.getElementById('input-binary').value.split(' ').map(byte => parseInt(byte, 16)); const disassembly = disassemble(binaryData); document.getElementById('output-disassembly').innerText = disassembly; }); This implementation provides a basic disassembler that can handle Z80 instructions with operands. However, it's incomplete and requires additional work to support all 252 instructions, operand types, and edge cases.
<script src="disassembler.js"></script> </body> </html>
switch (operandType) { case 'register': operandValue = getRegisterValue(binaryData, pc + 1); pc += 1; break; case 'memory_address': operandValue = getMemoryAddress(binaryData, pc + 1); pc += 2; break; case 'immediate': operandValue = binaryData[pc + 1]; pc += 1; break; default: throw new Error(`Unsupported operand type: ${operandType}`); } } return disassembly
operands.push(operandValue); }
In this post, we've explored the concept of a Z80 disassembler and provided a basic online implementation. While this implementation is incomplete, it demonstrates the fundamental steps involved in creating a disassembler. If you're interested in working with Z80 code or reverse-engineering old microcomputers, a Z80 disassembler is an essential tool to have in your toolkit.