I built a Game Boy emulator in F#

4 hours ago

The author built a Game Boy emulator called Fame Boy to learn how computers work, using F# for its strong type system and personal preference.
The emulator core has a simple interface with a framebuffer, audiobuffer, stepEmulator function, and getJoypadState callback, allowing it to run on desktop and web.
Functional programming principles were applied in modeling the CPU instructions, reducing 512 opcodes to 58 instructions while ensuring illegal states are unrepresentable.
Performance optimizations included removing unnecessary abstractions like a memory mapping DU, which doubled FPS, and using inline functions for flag operations.
Audio implementation was challenging; the emulator switched from frame-driven to audio-driven synchronization to avoid pops, though it remains a leaky part of the interface.
AI was used as an aid for writing tests, debugging, and performance improvements, but the author emphasized writing most code personally for learning and pride.
The project successfully ran on both desktop and web, with benchmarks showing good performance, and provided deep insights into computer hardware.

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