emulator: Arduous
type: libretro
source: "https://github.com/libretro/arduous"
profiled_date: "2026-03-18"
cores:
  - arduous
systems:
  - arduboy

notes: |
  Arduous is an Arduboy emulator built on simavr (ATmega32U4 AVR simulator)
  with SSD1306 OLED display emulation, ported to libretro. It is distinct
  from the Ardens core, which is a separate Arduboy emulator.

  No BIOS, bootloader, or system files are required. The core operates as a
  pure AVR simulator:

  - The game content (.hex Intel HEX format) is parsed at load time via an
    in-tree ihex reader (arduous.cpp:60-166) and written directly into the
    simavr flash memory at the address specified in the hex file
    (arduous.cpp:189). No separate bootloader is loaded.

  - The MCU is hardcoded to atmega32u4 at 16 MHz (arduous.h:70-71).
    simavr handles CPU initialization internally via avr_make_mcu_by_name().

  - A commented-out loadFirmware() function (arduous.cpp:22-29) suggests
    ELF firmware loading was considered but never implemented.

  - EEPROM (1024 bytes), system RAM, and VRAM are exposed via the libretro
    memory interface (RETRO_MEMORY_SAVE_RAM, RETRO_MEMORY_SYSTEM_RAM,
    RETRO_MEMORY_VIDEO_RAM) but are not loaded from external files.

  - The core never calls RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY. The
    retro_load_game() function only reads the content data buffer passed
    by the frontend (libretro.cpp:108-110).

  - RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME is set to false (libretro.cpp:123),
    meaning a game ROM is always required.

  Supported ROM format: Intel HEX (.hex) only. The valid_extensions field
  lists "hex". A TODO comment mentions .arduboy ZIP support but it is not
  implemented.

files: []