Sorry - yes, I meant the Cyclone cartridge. I have had an internal one in the past "back in the day". ASI released an internal and external one...
It seems similar to the external one that could be disabled, which allowed verifying and for it to be used as a standard floppy. IIRC it prevented you from having DF2 & DF3 though.
I don't know if the PAL was ever reverse engineered, it should be pretty trivial though. I don't think anyone bothered because the disabling wasn't very reliable, so you had to unplug it anyway & the verify wasn't worth the paper it was written on (by then cyclone was unable to copy a lot of copy protections anyway).