V-Max Copy Protection for Commodore 64 disk.
There was four main versions of this copy protection, then some versions with variations.
V-max protection was used my many different publishers including Activision, Cinemaware, Mindscape, Origin, Sega, Taito, Thunder Mountain and a few others.
There are already some great write ups on V-Max including this one from Pete Rittwage HERE: http://c64preservation.com/vmax
There was copiers that could make copies of V-Max software in the 1980’s like Burst Nibbler and Supercard. Plus many others that could copy a V-Max protected disk then you applied a parameter (crack) on the copy for it to work, like Disk Invaders, Fast Hackem, Maverick, etc.
There is also a NEW release in the V-Max copy programs called: Revolution V by Lord Crass. This program can be found here: http://csdb.dk/release/?id=134573
Even MORE information can be found here from a Post by Lord Crass made on the Lemon64 forums: http://www.lemon64.com/forum/viewtopic.php?t=53555&sid=9a9eb0a45e6d2d3935ec13d502aaeef5