Update the firmware to the most recent release.
Fixed the text rendering when double X is set (register $D001) to mimic machine.
F256K on MAME Instructions
Place the executable in a desired folder.
Create a sub-folder named "roms" and place the f256k.zip file in it, without decompressing.
Open a terminal window, such as "cmd" on Windows or bash in Linux.
For help, type ./f256 -h. On Windows, type .\f256.exe -h.
For usage info, type ./f256 -showusage. On Windows, type .\f256.exe -showusage.
To run in fullscreen mode, type ./f256 f256k. On Windows, type .\f256.exe f256k.
To use the provided SD card image, add -harddisk sdcard.img with the appropriate filename, of course.
To run in "windowed" mode, add -window -resolution 800x600 to get a resolution of 800 by 600.
You will have to study the MAME key codes to see how to get debugging going (backtick `` is the default).
You can turn off sound by adding -sound none to the command.