Emulations (running on Linux/Unix/Windows/macOS, utilizing SDL2) of some - mainly - 8 bit machines, including the Commodore LCD, Commodore 65, and the MEGA65 as well.
Summary: the character-WOM (also called just the WOM) is called WOM because it was Write-Only-Memory. It could be written by the CPU (only), and VIC-IV could (obviously) only read. However the problem was: freezer could not save the content of the "WOM" since it's not readable, and if user write into it, the state won't be intact anymore. Basically the mega65-core change makes the "WOM" (which shouldn't be called WOM anymore!! But I guess the name will survive ...) readable, thus freezer can save its state (and then restore, if needed).
See: https://github.com/MEGA65/mega65-core/issues/676 and https://github.com/MEGA65/mega65-core/issues/667
Summary: the character-WOM (also called just the WOM) is called WOM because it was Write-Only-Memory. It could be written by the CPU (only), and VIC-IV could (obviously) only read. However the problem was: freezer could not save the content of the "WOM" since it's not readable, and if user write into it, the state won't be intact anymore. Basically the mega65-core change makes the "WOM" (which shouldn't be called WOM anymore!! But I guess the name will survive ...) readable, thus freezer can save its state (and then restore, if needed).