JAXE
JAXE emulates CHIP-8.
About this profile
Platform details
-
bios_mapping:
- target: none
- source_ref:
libretro-core-info jaxe_libretro.info:17,src/chip8.c:118-168 - note: All font/sprite data is compiled into the binary. The standard CHIP-8 hex font (5 bytes per character, 16 characters) and the SCHIP big hex font (10 bytes per character, 16 characters) are stored as a static array in chip8_load_font() and copied into RAM on every reset. No file I/O is performed for BIOS or fonts.
Technical notes
JAXE is a CHIP-8, SCHIP, and XO-CHIP emulator by Kurtis Dinelle, ported to libretro. Supports .ch8, .sc8, .xo8, and .hc8 ROMs.
No external BIOS or font files required. The core has firmware_count = 0 in jaxe_libretro.info and never calls RETRO_ENVIRONMENT_GET_SYSTEM_DIR.
Font data is hardcoded in chip8_load_font() at src/chip8.c:118-168.
The standard 4x5 hex font (0-F, 80 bytes) is loaded at address 0x000,
and the SCHIP 8x10 big hex font (0-F, 160 bytes) follows immediately
after at address 0x050. Both are written directly into chip8->RAM[]
during chip8_reset() -> chip8_load_font().
Memory layout from include/chip8.h:42-45:
0x000-0x04F standard font (NUM_FONT_BYTES = 80)
0x050-0x0EF big font (NUM_BIG_FONT_BYTES = 160)
0x0F0-0x0FF stack (STACK_SIZE = 16)
0x100-0x10F audio buffer (AUDIO_BUF_SIZE = 16)
0x200+ program ROM (PC_START_ADDR_DEFAULT)
The fonts/dbgfont.ttf file in the repo is only used by the standalone
build (src/main.c:19) for the SDL debugger overlay, not by the
libretro core.
No BIOS or firmware files required.
Next steps
Section titled “Next steps”- Get your files, for the setup you play on
- Every system, and the files each one needs
- When a game does not start