The Ultimate Game Boy Talk (33c3)

I really like the Gameboy hardware; it's limited, but the design feels very elegant in it's simplicity. I've written a couple of toy Gameboy emulators at this point. It's a bit challenging to get anything working, and honestly I have no idea how to approach audio at all. Nevertheless, it's still quite fun. The LCD timings are a point of curiosity for me. It seems there's still a slight bit of mystery around it, still today. I was inspired to play with emulating Gameboy specifically after an excellent 33c3 talk, The Ultimate Game Boy Talk, which I highly recommend. [this video] (Some day I would like to approach emulation for more platforms, both newer and older, but I feel I still have so much time learn about designing emulators that I haven't bothered with that yet. It's so open ended, and handling things like cycle counting has a lot of different approaches of varying desirability.)

Game Boy emulators are always great for educational or experimental projects, because the Game Boy platform is surprisingly simple, which leads to a very quick payoff, and yet very "real" in that the Game Boy was a great commercial success with thousands of software titles available, so you have plenty of software available to try in your project and actually make use of that payoff. One example to illustrate how simple the Game Boy is: There is no operating system at all, only a 256 byte boot ROM whose sole purpose is to display the Nintendo logo from the cartridge and halt if it does not checksum correctly (for both cartridge integrity and legal reasons). This entertaining 33c3 talk manages to describe the Game Boy hardware practically in its entirety (and with some previously unknown details, actually): [this video]

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. [this video] 1. [link] 2. [link]

Modern Vintage Gamer just released a video [0] discussing this leak in greater detail along with its expected implications. Anyone who's curious can find the download links by backtracking through all the Pokemon Prototype General threads under the Pokemon board on 4chan. One of the leaks that caught my attention was the source for Pokemon Blue, partially because of nostalgia and partially out of curiosity to see what an old game's codebase even looks like. The first thing that stood out to me was the project's flat folder structure, full of hundreds of files; I guess I was expecting things to be a bit more structured. The source is more readable and approachable than I expected, although I've only poked around in some of the more obvious places and definitions. I'd recommend watching The Ultimate Game Boy Talk [1] before trying to dive into any code. [0] [link] [1] [this video]

Personally, I've had more trouble understanding the PPU behavior than i did about the cpu instructions and timings. I'd mostly been going off of The Ultimate Game Boy Talk[0] and the pandocs[1]. In trying to quickly dig up some resources now, I found what at first glance looks like a good blog series[2], so I might take some time to squint at them soon. If any HNer has other good resources describing it, I'd be thrilled. It's been a couple years since I've hacked on my own emulator, and I got through implementing quite a bit of the behavior. As I recall, I was able to get serial output from the test roms, which was pretty cool. I put it down after getting frustrated trying to render the screen. [0] [this video] [1] [link] [2] [link]