coffee-gb

Not a tutorial per-se, but here are 2 slides describing how I've done it: https://www.slideshare.net/slideshow/emulating-game-boy-in-j... Essentially, there are 4 channels, each providing a number 0-15 on every tick. Emulator should mix them together (arithmetic average), scale up to 0-255 and feed to the sound buffer, adjusting the tick rate (4.19MHz) to the sound output rate (e.g.: 22 kHz) - taking every ~190 value (4.19MHz / 22 kHz) is a good start. Now the 0..15 value that should be produced by each channel depends on its characteristics, but it's well documented: https://gbdev.gg8.se/wiki/articles/Gameboy_sound_hardware Channels 1 and 2 produce square waves, so a bunch of low (0) and high (15) values, with optional volume envelope (gradually going down from 15 to 0 on the "high" part of the square) and frequency sweep (alternating 0

Hey, SBC: result = byte1 - byte2 - carry carry = result < 0 return result & 0xff ADC: result = byte1 + byte2 + carry carry = result > 0xff return result & 0xff Source - my implementation, passes tests. Look for SBC & ADC in https://github.com/trekawek/coffee-gb/blob/master/src/main/j...

This talk inspired me to create a Game Boy emulator [1] and indeed it's enough to create a general design of each hardware subsystem (CPU, IRQ, Pixel Processor Unit, etc.) Also, the part about the pixel transfer is great, only few emulators implement it with FIFO queue, as presented, and this seems to be very accurate way. During the further work I needed more details (list of CPU opcodes, timing of the IRQs, a list of audio and timer bugs, etc.), but the list links to all required resources - as far as I know this is everything we know about the Game Boy at the moment. It doesn't mean the console is fully reverse-engineered - especially the STAT IRQ timings is still very hard to get right. Particularly interesting link is the "Pan Docs", moved and updated in the gbdev wiki [2]. Maybe it's not the best place to get the general information

Yet another Game Boy Color emulator, written in Java: https://github.com/trekawek/coffee-gb It's quite compatible and brought me a lot of fun. Blog post describing it: http://blog.rekawek.eu/2017/02/09/coffee-gb/