BootInvaders

A functional Space Invaders clone implemented entirely within a 512-byte x86 boot sector. Written in assembly (FASM) for the BIOS real mode.

Important

This is for educational purposes, demonstrating how to make a bootloader do interesting stuff.

Technical Specifications

Architecture: x86 (16-bit Real Mode)
Memory Address: Loaded at 0x0000:0x7C00 by the BIOS.
Display: VGA Mode 13h (320x200, 256-color linear framebuffer).
Video Memory: Direct writes to segment 0xA000.
I/O & Interrupts:
- int 0x10: Video services for mode setting and character output.
- int 0x16: Keyboard services for polling and reading scan codes.
- int 0x1A: Clock services used for frame timing and pseudo-random seed.
- 0x3DA: VGA Status Register polling for vertical retrace synchronization.

Double Buffering Simulation: Clears and redraws every frame synchronized with the vertical retrace to prevent flickering.
Physics & Collision: AABB (Axis-Aligned Bounding Box) collision detection for bullets, enemies, and player.
Procedural Respawn: Uses the system timer's lower bits to calculate the next enemy X-coordinate.
Score Tracking: Real-time score display using a custom decimal-to-string conversion routine.

# Compile the source to a 512-byte binary
make

# Run the binary in QEMU as a raw disk image
make run