Modern casino slot machines are controlled by a computer, and the winning %s are pre-programmed into the game software.
Casino Slots have Random # Generators which are eternally generating combos, even when the machine is not active.
Running in unison with the Random Number Generator of the casino one-armed bandit is the pay out percentage.
The pay out percentage controls how much the slot machine will pay, for example the pay out percentage could be 90%, which means the slot game will pay out ninety percent of all the wagers played, and the casino will then get to keep 10%.
This does not imply that each time you bet ten credits you will receive 9 in return – where is the fun and thrill in that? Instead, the casino slot machine game will not payout for a while, and then suddenly fire up a hot streak and you might hit a big grand prize.
The pay out %s most likely will vary between the different games and several of the very common casinos, for example Golden Online Casino, which puts forth a pay out of up to ninety five percent!
Thus, in essence, the slot machine takes all the $$$$$ played into it and pays it out to a few lucky winners. The casino only gets to keep a generally small % of all the wagers placed.
The casino one armed bandit software controls every single part of the machine, from the flashing lights to the circulating of the reels.
When you hit spin on the one-armed bandit, a combination is set up by the RNG which is linked to the pictures on the reel.