What is Continuous shuffling machine?
A continuous shuffling machine (CSM) is a device that reshuffles cards back into the blackjack shoe after each round, so the deck composition never depletes the way it does in a traditionally dealt shoe.
Traditional blackjack is dealt from a shoe that is reshuffled only after several rounds, which lets the ratio of high and low cards drift as the shoe is used up. A continuous shuffling machine removes this pattern by returning played cards to the shoe and reshuffling constantly, so the deck composition stays close to random at all times.
Casinos adopted CSMs largely to counter card counting, since the technique depends on tracking how the remaining shoe changes as cards are dealt. With a CSM in use, there is no meaningful depletion to track, which is one reason counting has become far harder than in the era of Edward Thorp and the MIT team.