As I understand it, today’s slot machines have a random number generator that continuously generate a random number until the user hits the “Bet” button. The machine then looks up the payout for that number and spins the wheels to the appropriate combination. Multi-line machines allow a player to play multiple lines per spin. On the mechanical versions that I have seen, there is always a blank space after each image on each reel. If I’m playing 3 lines where each line across the machine is in play, how could the machine position the reels so that each line is a winner? If the RNG were to show that all 3 lines were to win, would the machine combine winnings into 1 line or do the IGT people not want us to think about it too much?
Long time lurker uncloaking.
You are correct in your understanding that the outcome of the game is decided by the machine’s software at the time the “Bet” or “Spin” button is pressed or when the first coin is dropped in the slot if there are no credits on the machine.
A little further understanding: On the old type “mechanical” slot machines pulling the handle compressed a spring which set the reels in motion; the positions in which the reels stopped decided the payout. On modern “electronic” slot machines the payout is decided by the software, then the reels are used only to display the outcome, not to decide it.
The relevant part: The “physical” reels on a modern electronic slot machine do not necessarily accurately represent the “virtual” reels in the software.
The physical reels may each have, say, ten symbols and ten blanks. On a mechanical machine you could then use 20 x 20 x 20 to figure the total number of possible combinations, then use the payout chart to figure the exact percentage of payback on the machine.
On an electronic machine the physical reels may have the same ten symbols and ten stops, but the virtual reels, which are what actually decide the outcome, may have ANY number of virtual stops, e.g., a physical reel shows four 7s, six Cherries and ten blanks, however, the virtual reel contains one 7, two Cherries and 33 blanks. The casual player has no way to determine the contents of those virtual reels, hence no way to determine the percentage payback of the machine.
The actual answer: The reels on a modern electronic slot machine are only a display device; they play no part in determining payouts. The position in which the reels will stop is decided in advance by the software.