espboy_emulator

An emulator for the Espboy using SDL3

Project maintained by joyrider3774 Hosted on GitHub Pages — Theme by mattgraham

The ESP8266 ROM

The emulator boots the way the real chip does: through the ESP8266’s own 64 KB mask ROM. That ROM belongs to Espressif and is not included with the emulator; you read it out of any ESP8266 board yourself. It is the same in every ESP8266EX (an ESPboy, a Wemos/LOLIN D1 mini, a NodeMCU, an ESP-01…), and reading it changes nothing on the board.

Put the file, named esp8266_rom.bin, in this bios folder next to the emulator. (It is also found next to the emulator itself, in the current folder, or wherever --rom or the ESPBOY_ROM environment variable points. On macOS: in a bios folder next to the .app.) For the web version, put it next to ESPboy_Emulator.html.

Reading it with esptool

  1. Install esptool: pip install esptool (Python 3).
  2. Connect the board with USB and find its serial port: COM3 or similar on Windows (Device Manager, “Ports”), /dev/ttyUSB0 or /dev/ttyACM0 on Linux, /dev/cu.usbserial-* or /dev/cu.wchusbserial* on macOS. The ESPboy uses a CH340 USB serial chip; Windows and macOS may need its driver.

  3. Read the ROM:

    esptool --chip esp8266 --port COM3 --no-stub dump_mem 0x40000000 0x10000 esp8266_rom.bin

    (older esptool versions are called as esptool.py). It takes a few seconds. The result must be exactly 65536 bytes; some esptool versions print an error at the very end although the file is complete.

With the emulator’s source, python tools/get_rom.py COM3 does the same and puts the file here. It finds esptool in Python or in the Arduino IDE’s esp8266 core.