IrisGBC - Native GB/GBC Emulator

IrisGBC is a full GameBoy (DMG) and GameBoy Color (CGB) emulator built from scratch using a single tool: VBA. It runs entirely inside Microsoft PowerPoint, turning your presentations into a window to 8-bit classics.

This project was born as a challenge: would it be possible to faithfully recreate a complex hardware system in such a restricted scripting environment? The answer is here. Every CPU instruction, every pixel on the screen, and every timer tick are handled by pure VBA code, with no external libraries.

Main Features

• CPU Core: Emulation of the Sharp LR35902 processor, optimized for performance in VBA using techniques like lookup tables (LUTs).
• Graphics Rendering (PPU): Full support for background, window, and sprites, including priorities and the LCD state machine.
• Accurate Timing: Timer and Interrupt systems implemented to ensure games run at the correct speed and that events (such as music and animations) stay synchronized.
• Intuitive Controls: Play using the keyboard with classic key mapping.

Challenges and Solutions

The biggest challenge was overcoming VBA's performance limitations. The key strategies include:

• Fine Synchronization: The main loop operates in short “ticks,” updating all components with the exact cycle count of the last instruction, ensuring accuracy and UI responsiveness via DoEvents.
• Critical Path Optimization: Functions executed millions of times, such as pixel decoding, were replaced with precomputed lookup tables (LUTs).
• Low-Level Operations: Avoiding function calls like Abs() in favor of bit operations (And, Or) and integer negation -(condition) to manipulate flags.