THthristian·Sep 24, 2021
See also https://github.com/Gekkio/mooneye-gb which is more famous for its exhaustive test suite than its emulation accuracy.
In RBoy: A Gameboy Emulator in RustGekkio
mooneye-gb
Rust2017–2021
Gekkio / mooneye-gb
mooneye-gb
A Game Boy research project and emulator written in Rust
5Distinct people
5Mentions
1Explicit recommenders
972GitHub stars
What to know before exploring
What it is
A Game Boy research project and emulator written in Rust
GitHub
Where it is used
No documented product use has been verified yet.
What people are saying
I've been working on a GB emulator for awhile. Step one is to understand the architecture of the system. What are the different hardware components? How do they interact? A…
ehaskins used a recommendation phrase. One indexed comment matches. This is a phrase match, not a verdict.
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This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by year5 dated mentions
Observed mentions: 2017-12-09 05:40:46 UTC to 2021-09-24 07:20:52 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2017 | 2017-01-01 00:00:00 UTC | 2018-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2018 | 2018-01-01 00:00:00 UTC | 2019-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2021 | 2021-01-01 00:00:00 UTC | 2022-01-01 00:00:00 UTC | 1 | 0 | 1 |
What Hacker News says
5 sourcesA few months ago the whole GameBoy SoC (DMG-CPU) was reversed engineered in the same way [1], except for the CPU part - this means the schematics include pixel processor unit, timer, serial port, IRQ controller, etc. However, it seems that the CPU itself is pretty straight-forward to emulate anyway, since Gekkio, author of the mooneye-gb [2], figured it's a variant of a well-documented SM83.
Anyway, reverse-engineering efforts like this are pretty exciting, as they should allow to create a 100% accurate emulators - and we know they are accurate not only because all the games are running as expected, but because they are based on the actual hardware design (which is even better than the producer's specification).
GB is not a complex piece of hardware, in comparison to eg. SNES, but there are some emulation issues really hard to tackle, esp
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ecially around the pixel processing unit IRQ timings - it's like solving a complex set of linear equations, but we don't even know what the variables are (eg. what can affect a 4-processor-tick shift in the HBlank IRQ timing this way or another).
Looking forward to a complete, transistor-level GB simulator, something like Visual6502.
[1] https://github.com/furrtek/DMG-CPU-Inside
[2] https://github.com/Gekkio/mooneye-gb
[3] http://www.visual6502.org/
I've been working on a GB emulator for awhile.
Step one is to understand the architecture of the system. What are the different hardware components? How do they interact?
A simple emulator boils down to:
While(true)
Emulate_one_cpu_cycle()
For each cycle you have to produce any side effects from the various peripherals (serial comms, update the display, generate audio, etc.), process any external changes (button presses, serial data), and emulate the next CPU instruction (basically a big switch).
I recommend "The Ultimate Gameboy Talk (33c3)" [0], for an overview of the Gameboy and it's internal peripherals.
There are various test ROMs available that you can use to verify the basic functionality. [1][2]
0. https://m.youtube.com/watch?v=HyzD8pNlpwI
1. http://gbdev.gg8.se/wiki/articles/Test_ROMs
2. https://github.com/Gekkio/mooneye-gb
In GameBoy CPU Manual (2013) [pdf]Writing Gameboy emulator is fun, just like writing a raytracer. And it can be nice way to learn a new language. Is there something special/different in this project compared to many others?
For me the most interesting GB emulation project is Mooneye due to being written in Rust and its emphasis on accuracy and documentation of GB hardware: https://github.com/Gekkio/mooneye-gb
In GameLad – Gameboy emulator written in C++i have been writing a gameboy emulator for the last year (with short bursts of work where i implement some module), and it's been very challanging and fun, i recommend everyone to try it.
it has a very simple 8-bit (risc) architecture, but obviously tailored for games (for example, it has a dedicated sprite memory sector). i recommend people to try it out because it is has fun quirks compared with "regular" architectures, like arm and x86, for example in the way it handles cartridges, or in that some cartridges actually had non-trivial logic inside them and weren't just a rom.
it always amazes me how active gameboy research and development is still today, for example there's a very recent gameboy emulator / research project done in rust https://github.com/Gekkio/mooneye-gb
there are even test roms with which you can test your emulator to
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see if it implements all opcodes, interrupts and whatnot correctly (where correctly not only means "with respect to the effects" but also with respect to how many cycles everything should take). example of these test roms: http://gbdev.gg8.se/files/roms/blargg-gb-tests/
also for example this disasm of pokemon red: https://github.com/pret/pokered
if you want to write an emulator or a game and you have basic computer organization knowledge, i'd start with the famous pandocs.