Trying to remember something I accidentally found online about a decade ago, and even then it was old stock at liquidation prices 😀

This product would technically be a card but I'm fairly sure it only was a ROM and all the magic was in software (probably DOS/9x and FAT-centric);
basically it made a copy of your "HDD" on another partition, hid it with a custom int13 driver almost like an HPA, and on demand or every boot it would restore the image so that you'd have a clean and known starting condition...

What was this called? (tried to search for variations of "isa backup card" with no real success)
And of course: did it really work with a contemporary OS, and is it terribly broken with anything else?

Thanks in advance 😀