Guide to making a CHIP-8 emulator
12 days ago
- #retro-computing
- #emulator-development
- #CHIP-8
- CHIP-8 is a virtual machine created in 1977 by Joe Weisbecker for the COSMAC VIP microcomputer, designed to simplify programming.
- CHIP-8 programs are interpreted, not emulated, as they don't run on physical hardware but a virtual machine.
- The CHIP-8 interpreter includes components like memory (4KB RAM), a 64x32 monochrome display, 16 general-purpose registers, and two timers (delay and sound).
- Key instructions include display drawing (DXYN), jumps (1NNN), subroutine calls (2NNN), and arithmetic/logical operations (8XY series).
- CHIP-8's display is updated by XORing sprite data with the screen, causing flickering effects when sprites are moved.
- Input is handled via a hexadecimal keypad, typically mapped to a QWERTY keyboard in modern emulators.
- Ambiguities in CHIP-8 specifications exist due to different historical implementations, requiring emulators to handle quirks like shift behavior (8XY6/8XYE) and memory operations (FX55/FX65).
- Testing CHIP-8 emulators can be done using programs like the IBM logo or test ROMs (e.g., BC_test, chip8-test-rom).
- Extensions like SUPER-CHIP (higher resolution, scrolling) and XO-CHIP (more colors, sound) expand CHIP-8's capabilities.
- Future projects could include adding debug tools, supporting SUPER-CHIP/XO-CHIP, or porting the emulator to obscure platforms.