Beyond CHIP-8

CHIP-8 is just the start. Same patterns scale up:

NES (Nintendo Entertainment System):

• 6502 CPU (simple 8-bit processor).
• 2 KiB RAM.
• PPU (Picture Processing Unit): tile-based graphics, 64 sprites.
• APU (Audio Processing Unit): 5 audio channels.
• Mappers: cartridge-side memory bankers.
• ~3500 LOC for full emulator.

Game Boy:

• Custom 8-bit CPU (Z80-like).
• 8 KiB RAM, 8 KiB VRAM.
• LCD: 160x144, 4 shades of grey.
• Sound: 4 channels.
• Famous test ROMs: Blargg's tests, mooneye.
• ~5000 LOC for cycle-accurate.

SNES (Super Nintendo):

• 65816 CPU + dedicated sound CPU.
• Mode 7 graphics (rotation/scaling).
• Much harder to emulate accurately.

N64, PS1, GameCube:

• 3D capable.
• Custom GPUs harder than the CPU.
• Most emulators use HLE (high-level emulation): pretend to be the GPU.

Modern emulator architecture:

• CPU core: same fetch-decode-execute loop.
• Bus / memory map: route accesses to RAM, ROM, MMIO.
• PPU/GPU: render frames (often run in parallel thread).
• APU: audio (callback into audio output).
• Input mapping: keyboard/gamepad → emulated buttons.
• Save states: serialize entire state to disk.
• Rewind: keep N seconds of states, playback in reverse.

JIT (Just-In-Time):

• Recompile guest instructions to host code on the fly.
• 10-100x speedup.
• Used by QEMU TCG, Dolphin (GameCube/Wii).

Cycle-accurate vs HLE:

• Cycle-accurate: emulate exact timing. Plays glitchy games correctly.
• HLE: skip exact timing for performance.
• Modern emulators offer both modes.

Real-world emulators:

• Mesen (NES): cycle-accurate.
• Dolphin (GC/Wii): HLE.
• MAME: thousands of arcade games, ports of every CPU.
• RPCS3 (PS3): in development.

For learning:

• CHIP-8: 1-3 days.
• Game Boy: 2-4 weeks.
• NES: 3-6 weeks.
• SNES: months.
• Modern consoles: years + reverse engineering.

The lessons compound: write CHIP-8 → understand instruction decoding. Write GB → understand interrupts, banking. Write NES → understand PPU + DMA + mappers. By PS1, the patterns are familiar; just more of them.

Don't roll your own for production. Use existing emulator if you want to play games. Roll your own to learn.