The RNG is always working, even when you’re not playing, picking hundreds of random numbers per second. (NV Gaming Regulations, Technical Standards, 1.400) The moment you press the button or pull the lever, the RNG picks its 3 or 5 numbers for your play. So if someone hits a jackpot on a machine you were just playing, relax, you wouldn’t have gotten it had you kept playing, because you would have hit SPIN at a slightly different time than they did. Every fraction of a second you delay in hitting the SPIN button results in a different combination.
The reason the machine constantly picks numbers is so that no one can discern any pattern in the number-picking process and there slotxo fore predict a winner. It’s extremely unlikely that anyone could do so even if the RNG didn’t keep picking random numbers all the time, because the number of random numbers in a complete cycle is astronomical, but having the RNG pick numbers all the time removes even the fantastically remote possibility that anyone could predict the outcome.
Slot makers create a “Par sheet” for each slot which lists the reel symbols and the paytable. From this the payback can be calculated, and a programmer can write the computer code for the slot. This data is similar to the tables I provided above for my fictional slot. I have a separate page about par sheets, along with several actual examples.
Earlier we saw how the symbols on electromechanical slots are weighted. There are only 11 blanks on the physical reel, but chances the RNG will pick a blank is much higher than 1 in 11. In fact, it will favor the blanks immediately above and below the jackpot symbol. Hitting these blanks gives players the illusion that they almost landed the jackpot symbol, because the jackpot symbol is physically close to the payline. But it’s not mathematically close. In reality, the player wasn’t close to landing the jackpot symbol on the payline at all.As you might expect, research shows that the near-miss effect keeps players playing longer. (Journal of Gambling Studies)The Wizard of Odds cites an unnamed source who said that Nevada regulations say that a stop on a reel can’t be weighted more than six times more than either stop next to it. (link) However, I scrutinized Regulation 14 and can’t find any such requirement.
Video slots show the actual reels rather than virtual reels. As such, the kind of near-miss described above won’t artificially appear on video slots. (In theory, there might be some video slots that use virtual reels, but I haven’t seen any evidence of this.) However, video slots use another method to make a near-miss effect: they put fewer jackpot symbols on the 4th and 5th reels vs. the 1st, 2nd, and 3rd reels. When players line up the symbol on the first three reels they’ll feel they were close to getting a 4th and maybe 5th symbol, but the reality is that it’s much harder to get those right-hand symbols.In 1988, it was discovered that certain machines were using a different, illegal kind of near-miss technology. The slot would first choose the stops randomly, and if it was a losing combination, rather than showing the actual combination selected, it would choose another combination to display, which was more likely to show jackpot symbols just above or below the payline. (source)