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Overview

How do emulators work? That is the goal of this project. Just learn the rough process to emulate a Gameboy. The first step is to setup a basic game loop as you might for any other game. This should initialize your render library (SDL2 in this case). In the game loop you will then want to execute one video frame of CPU cycles, then render the screen, and then wait any extra time to ensure your processor and video are running at the correct speed.

Key Links: http://problemkaputt.de/pandocs.htm

Part 1

How long is one frame on the Gameboy? If you look in the link above and find the "Game Boy Technical Data" section, you will see that vertical sync is 59.73 Hz. This means, we need to render about 60 frames per second.

How may cycles does the Gameboy CPU process in one frame? If you look in the link above and find the "LCD Status Register" section, you will see that a complete screen refresh occurs every 70,244 clock cycles. The CPU should continue processing OpCodes until it meet or exceeds 70,244 clock cycles and then return to allow the emulator to refresh the screen.

Part 2 - The CPU

A CPU is the brain of the emulator. It is responsible for tracking the state of memory, registers and executing code. CPU Register and Flags are fundamental. They are accessed often and change regularly. The first part of CPU implementation is getting the registers and flags setup.