DocBoy

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What DocBoy is

DocBoy is an open source emulator for the original DMG GameBoy and the CGB GameBoy Color. Written in C++17, it models CPU operations at machine-cycle accuracy and graphics processing at clock-cycle accuracy with a Pixel FIFO. It supports NoMBC, MBC1, MBC2, MBC3, MBC5, MBC7, HUC1, and HUC3 cartridges, along with audio, link cable emulation, and a real-time clock.

DocBoy’s frontends provide save and load, save states, fast-forward, configurable palettes, screenshots, and an SDL graphical menu. An optional GDB-style command-line debugger includes disassembly, breakpoints, watchpoints, stepping, rewind, and memory viewing. The emulator can also run as a libretro core with RetroArch. Windows and Linux executable releases are available, and the project documents how to build an Android libretro core. RetroArch supports platforms including Android and iOS. DocBoy is free and licensed under MIT. The project says perfect emulation remains a distant goal and that accuracy may affect performance. It invites bug reports, failing test ROM reports, and feature proposals through issues and pull requests.

Who it suits

DocBoy suits people looking for an open source emulator for the original GameBoy or GameBoy Color, including users who want save states, configurable palettes, or debugging tools. It is also an option for RetroArch users who want to run it as a libretro core.

What it does well

Emulates the original DMG GameBoy and CGB GameBoy Color.
Supports eight listed cartridge types.
Includes save states, fast-forward, screenshots, and configurable palettes.
Offers an optional debugger with breakpoints and rewind.
Can run as a libretro core with RetroArch.
Released under the MIT license.

What to know first

The project says perfect emulation remains a distant goal.
The project warns accuracy may come at some performance cost.
Executable releases are listed for Windows and Linux; Android requires a libretro build.

Limits

The project says perfect emulation remains a distant goal and that accuracy may affect performance.

Getting started

Visit the DocBoy GitHub repository.
For Windows or Linux, get an executable from the project’s releases.
For Android, follow the documented steps to build the libretro core.
Load the libretro core through RetroArch, which supports Android and iOS.

Verdict

Choose DocBoy if you want a free, open source emulator with detailed CPU and graphics emulation, save states, and an optional debugger. Consider the project’s stated accuracy and performance caveat when choosing it, and note that the documented executable releases are for Windows and Linux.

Questions

Is DocBoy free?

DocBoy is described as free and is licensed under MIT.

Which systems does DocBoy emulate?

It supports the original DMG GameBoy and CGB GameBoy Color.

Which platforms can run DocBoy?

The project points to executable releases for Windows and Linux and documents an Android libretro build. Through RetroArch, libretro use is described for platforms including Android and iOS.

Does DocBoy support save states?

Yes. Its frontends include save states, as well as save and load.

Can DocBoy work with RetroArch?

Yes. DocBoy can run as a libretro core with RetroArch.

What license does DocBoy use?

The repository identifies the license as MIT.

Facts from DocBoy's own pages

Accuracy: The emulator uses M-cycle accurate CPU emulation and T-cycle accurate PPU emulation with a Pixel FIFO. · github.com, 7 Oct 2026
Accuracy caveat: The project says perfect emulation remains a distant goal and that accuracy may come at some performance cost. · github.com, 7 Oct 2026
Cartridges: Supported cartridge types include NoMBC, MBC1, MBC2, MBC3, MBC5, MBC7, HUC1, and HUC3. · github.com, 7 Oct 2026
Contributions and support: The README invites bug reports, failing test ROM reports, and feature proposals through issues or pull requests. · github.com, 7 Oct 2026
Debugger: An optional GDB-style CLI debugger supports disassembly, breakpoints, watchpoints, stepping, rewind, and memory viewing. · github.com, 7 Oct 2026
Downloads: The README points to releases with executables for Windows and Linux. · github.com, 7 Oct 2026
Downloads and builds: The README says executable releases are available for Windows and Linux, and describes an Android libretro build option. · github.com, 7 Oct 2026
Emulation: The README lists an M-cycle-accurate CPU, a T-cycle-accurate PPU, audio, and emulation for multiple cartridge types. · github.com, 7 Oct 2026
Frontend features: Its frontends provide save/load, save states, fast-forward, configurable palettes, screenshots, and an SDL graphical menu. · github.com, 7 Oct 2026
Integration: DocBoy can run as a libretro core with RetroArch. · github.com, 7 Oct 2026
License: The repository identifies its license as MIT. · github.com, 7 Oct 2026
Limit: The README says perfect emulation remains a distant goal and that accuracy may come at some cost to performance. · github.com, 7 Oct 2026
Maker location: The maintainer's GitHub profile lists Italy. · github.com, 7 Oct 2026
Mobile support: The project documents building an Android libretro core, and says RetroArch supports platforms including Android and iOS. · github.com, 7 Oct 2026
Mobile use: The README says the libretro core can be loaded through RetroArch, which it describes as supported on platforms including Android and iOS. · github.com, 7 Oct 2026
Other features: The frontends include save/load, save states, fast-forward, configurable palettes, screenshots, and an SDL graphical menu. · github.com, 7 Oct 2026
Pricing: The repository describes DocBoy as open source but does not state a price or offer a trial. · github.com, 7 Oct 2026
Product: DocBoy is an open source GameBoy emulator written in C++17. · github.com, 7 Oct 2026
Support: The project invites bug reports and feature proposals through issues and pull requests. · github.com, 7 Oct 2026
Systems emulated: It supports the original DMG GameBoy and CGB GameBoy Color. · github.com, 7 Oct 2026

Where DocBoy stands on Freedom251

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