Modern casino Slots are controlled by computer software, and the win percentages are preprogrammed into the software.
Casino slot machine games have Random Number Generators which are continually generating combos, even when the slot machine game is not active.
Running synchronously with the random # generator of the casino slot machine game is the pay out %.
The payout per cent controls just how much the slot machine will pay out, for e.g. the pay percent could be ninety per cent, which means the slot game will pay ninety percent of all the wagers played, and the casino only gets to keep 10 percent.
This is not to say that each and every time you bet 10 credits you will receive 9 in return – where is the fun … excitement in that? Instead, the casino slot just will not payout for a while, and then suddenly jump on a hot streak and you might hit a big top prize.
The payoff %s will very likely vary between the various games and a couple of the highly established casinos, for e.g Golden Online Casino, which offers a pay out of up to ninety five percent!
Thus, in essence, the slot machine game takes all the cash played into it and pays it out to a number of lucky winners. The casino only gets to keep a relatively indistinct % of all the odds allotted.
The casino slot software controls every part of the machine, from the blinking lights to the revolving of the reels.
When you hit spin on the one-armed bandit, a combination is put together by the RNG which associates with the pictures on the reel.