ESP firmware for DreamcastHDMI/DCHDMI consists of 2 files
    
        - <flash_size>-firmware.bin
The firmware itself. 
        - <flash_size>-spiffs.bin
Flash filesystem. 
    
    Additionally there is the index.html.gz for this version for WiFi-update
    
        - esp.index.html.gz
index.html file for self-update.