Z80: Disassembler Online Full |link|

Finding a high-quality "full" online Z80 disassembler is a common request for retro computing enthusiasts working on ZX Spectrum, Amstrad CPC, or TI-84 calculator projects. Many web-based tools are lightweight, but a few stand out for their features and community recognition. Highly Rated Online Z80 Disassemblers

Several platforms offer robust disassembly directly in the browser:

Ghidra. 2023. Available online: https://ghidra-sre.org/ (accessed on 25 September 2023). Binary Ninja

Binary Ninja Cloud is our free, online reverse engineering tool. It supports a number of great features. Binary Ninja

Assuming you won't/can't/don't want to use WinDbg to analyze, another options is to submit it online to be analyzed for you.

The Online Disassembler (onlinedisassembler.com) is frequently cited by the reverse engineering community. It supports multiple architectures including the Z80 and allows you to upload binary files for interactive analysis.

David Gom's Z80 Disassembler is a classic "browser-based" tool. Although the original site has experienced downtime, it is still accessible via the Internet Archive. It was noted for being extremely fast, handling large programs like zStart 1.1 in under a second.

Binary Ninja Cloud provides a high-level, free online reverse engineering platform. While it is a modern general-purpose tool, it has excellent Z80 support with advanced features like control flow graphs and lifting to intermediate languages.

ClrHome's Z80 Assembler/Disassembler is another popular online choice, particularly for TI-83 and Spectrum series development. Comparison of Features Key Strengths Online Disassembler Broad architecture support, interactive UI Quick file analysis without installation Binary Ninja Cloud Control flow graphs, modern UI, deep analysis Serious reverse engineering projects David Gom (Archived) Pure speed, lightweight engine Fast-paced coding sessions ClrHome Built-in editor and assembler Integrated dev for specific retro targets Notable "Smart" & Pro-Level Alternatives

If online tools feel too limited for your project, experts often point toward these more powerful (but downloadable) solutions:

Ghidra: An NSA-developed, free, and open-source suite. It is one of the most powerful options available today, capable of turning Z80 assembly into readable pseudo-C code to help you understand complex logic.

z80-smart-disassembler: A specialized tool on GitHub designed to take the "effort" out of reversing. It automatically identifies and labels strings and data areas, which is a major time-saver for large binaries.

IDA Pro (Free version 3.7): While dated and no longer officially distributed, this specific version of IDA supports Z80 and is still praised for its high-level analysis capabilities. z80 disassembler online full

💡 Pro-Tip: When using online disassemblers, ensure you know your file's load address (the memory location where the code starts). Many tools will fail to produce correct labels or jumps if the origin address is set incorrectly.

What system is the code for (e.g., ZX Spectrum, TI-83, Amstrad)?

Are you disassembling a small snippet or a full ROM/snapshot? Do you need to reassemble the code afterward?

Ghidra. 2023. Available online: https://ghidra-sre.org/ (accessed on 25 September 2023). Binary Ninja

Binary Ninja Cloud is our free, online reverse engineering tool. It supports a number of great features. Binary Ninja

Assuming you won't/can't/don't want to use WinDbg to analyze, another options is to submit it online to be analyzed for you. JEB decompiler

Several online platforms and tools allow you to disassemble Z80 machine code directly in your browser or through modern web-based interfaces. Top Online Z80 Disassemblers

These tools are specifically designed for web use, allowing you to paste hex code and receive readable assembly. Z80.info - Online Disassembler

: A long-standing repository of Z80 tools that lists several web-based and lightweight disassembling utilities. Cemetech Online Z80 Disassembler

: A fast, browser-based tool originally developed for TI calculator enthusiasts but capable of handling large binary files quickly. ClrHome Z80 IDE

: While primarily an online assembler, it features a robust interface and integration for managing Z80 source code and exports. nedoPC.org Online Disassembler

: A universal online tool that supports i8080, i8085, and Z80 architectures, frequently used for researching vintage computer ROMs. Advanced & Desktop-Adjacent Tools Finding a high-quality "full" online Z80 disassembler is

If you require more "full" features like data/code separation or template overrides, these more advanced tools are highly recommended: Z80 Smart Disassembler (GitHub)

: A modern "smart" tool that attempts to automatically identify and label strings and data areas to save manual effort. YAZD (Yet Another Z80 Disassembler)

: A powerful command-line tool that can generate hyperlinked HTML output files, making it easy to browse the disassembled code in a web browser. DeZog Debugger

: A VS Code extension that integrates a full-featured Z80 disassembler into a modern development environment. Key Considerations for Disassembly

When using these tools, you will often need to provide specific information for an accurate "full" disassembly: GitHub - cormacj/z80-smart-disassembler

A comprehensive Z80 online disassembler is an essential tool for retrocomputing enthusiasts and reverse engineers. It transforms raw binary machine code into human-readable assembly language, allowing you to study classic software from systems like the Sinclair ZX Spectrum, Amstrad CPC, and MSX. Core Features of a "Full" Disassembler A top-tier online tool typically includes:

Intelligent Analysis: Automatically distinguishes between executable code and data areas (like sprites or text strings) to prevent "gibberish" output.

Symbol & Label Support: Generates meaningful labels for jump targets and memory addresses instead of just raw hex values.

Support for Undocumented Opcodes: Accurately decodes the "hidden" Z80 instructions often used in early software protection schemes or optimizations.

Interactive Editing: Allows users to manually mark specific memory regions as code or data to refine the disassembly results.

Format Versatility: Handles various file types, including raw binary (.bin), Intel HEX, and machine-specific snapshots like Spectrum .sna files. Why Use an Online Version?

Zero Installation: No need to compile complex C libraries or set up legacy environments; it works directly in any modern browser. Step-by-Step: How to Use a Z80 Disassembler Online

Cross-Platform: Accessible on Windows, macOS, or Linux, making it ideal for quick sessions or collaborative debugging.

High Speed: Modern JavaScript engines often process small-to-medium ROM files almost instantly. Popular Tools & Alternatives

Online Assembler and Disassembler (Shell-Storm): A fast, web-based tool supporting multiple architectures including Zilog Z80.

ClrHome ORG: A specialized online IDE frequently used by the TI-83 graphing calculator community for Z80 development.

Ghidra / radare2: For professional-grade reverse engineering, these free, open-source tools offer deep Z80 support and powerful tracing capabilities. GitHub - cormacj/z80-smart-disassembler

Step-by-Step: How to Use a Z80 Disassembler Online Full

Let’s walk through a practical example. Imagine you downloaded a 16KB ROM file for a classic ZX81 or a vintage arcade game.

Step 1: Find a Reputable Tool Search for "Z80 Disassembler Online" and look for one that explicitly lists "full" or "professional" features. Sites like Defuse.ca, Masswerk.at, or Omegatrix are good starting points. (Note: Always check the tool’s feature list against the checklist above).

Step 2: Load Your Binary Use the "Load File" or "Paste Hex" option. Full tools support drag-and-drop. You might need to tweak the Origin (starting address). If your ROM is designed to run at address $0000, set the origin to 0. If it’s a ZX Spectrum snapshot at $4000, set the origin accordingly.

Step 3: Configure the Options

CPU: Select Z80 (some tools also handle 8080 or Game Boy LR35902 – ensure you are on true Z80 mode).
Undocumented: Check "Include undocumented opcodes."
Code Analysis: Select "Recursive Traversal" or "Smart Disassembly."

Step 4: Run the Disassembly Click "Disassemble." Within milliseconds, the tool will produce a listing. You will see something like:

0000  C3 20 10   JP   $1020
0003  00         NOP
...
1020  AF         XOR  A
1021  32 00 50   LD   ($5000), A

Step 5: Analyze and Annotate Now the magic of a full tool happens. You will start labeling:

Right-click on $5000 and label it VIDEO_MEMORY.
Search for ASCII strings; if you find "GAME OVER" at $2000, tell the disassembler that region is data, not code.
Add comments explaining what each subroutine does.

Popular Use Cases

Retro computing: reverse-engineering ROMs for Spectrum, MSX, Game Boy (CPU-compatible), etc.
Education: learning Z80 instruction set by observing compiled/assembled binaries.
Patching: making small fixes or translations to classic software.
Emulator development: verifying CPU behavior and edge cases.

4. Output to Standard Formats

Can you export your work as a .ASM file compatible with SjASM, RASM, or Z80ASM? A full online disassembler allows you to download the commented listing for reassembly.