Fabian90,

Systems that don't require a "true count" conversion are called "unbalanced" systems: instead of using the TC for betting and playing decisions, unbalanced systems use just the running count (RC). Thus, KO is an unbalanced system. Since KO uses card tags of -1, 0, and +1 only, KO is called a "Level 1" system. For that matter, HiLo is also a Level 1 system.

One very powerful unbalanced system is the "Unbalanced Zen2" system (also known as UBZII). UBZII is a Level 2 unbalanced system that was developed by a long-time (and still current) player writing under the handle "George C." His book is available in a Kindle edition from Amazon: go there and search for "The UnBalanced Zen2".

Hope this helps!

Dog Hand