Clearing up "What happens when a slot machine is reset?" starts inside the cabinet. A slot machine looks like a game of reels, but what decides every payout is a random number generator working out of sight. The reels, the paylines and the buttons on the screen only show a result that was fixed the moment the spin began. Knowing how that works, from mechanical machines to modern video slots with megaways and bonus rounds, clears up most of what players wonder about them.
Slot machines determine a payout in two steps. A random number generator picks a result the instant the spin button is pressed, and the pay table converts that result into a win or a loss. Slots are actually random in this sense: no spin remembers the last, and a machine is never due. What the operator sets is the return to player, the share of stakes paid back over millions of spins, which is fixed in the game's code.
A few questions come up about what happens behind the scenes. When a slot machine is reset after a jackpot or a fault, nothing about its odds changes; the generator keeps running. When a machine malfunctions, the rule printed on most games voids pays and plays, and the logged result settles any dispute. Slot machines cannot be adjusted on the floor without approval and new software. Hacked machines are a rare crime, not a player strategy, and old slot machines are usually scrapped or sold to collectors.
Older mechanical slots work with physical reels and a coin mechanism: a coin drops past sensors that check its size and weight, a lever or button releases the reels, and stops on each reel decide the symbols. Class II slots, found in some venues, work differently again: each spin is really a round of bingo against other players, and the reels simply display the outcome of that draw in a familiar shape.
Quick answers
When is the result of a slot spin decided?
A random number generator picks the outcome the instant the spin button is pressed; the reels only display a result that is already fixed.
What stops a slot autoplay run early?
Autoplay runs a chosen number of spins automatically, and limits set on total losses or on a single large win halt it before the count runs out.
Who sets a slot's return to player?
Return to player, the share of stakes paid back across millions of spins, is chosen by the operator and fixed in the game software rather than adjusted between spins.
What is a Class II slot machine?
Each spin on a Class II machine is really a round of bingo against other players, and the reels simply present that draw's result in a familiar form.