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# Polling the RNG

11 April 2004

Hey, John,

Great info on slot machines. Let me ask you: On two or three-coin slot machines, is it true that as soon as you drop the first coin you stop the RNG? I know I read it somewhere.

Thanks,
Joe

Dear Joe,

Thanks for the kind words about my column.

The RNG never really stops running. When the computer program running the machine needs to know which symbols to land on the payline, it gets the current number generated by the RNG. This process is known as polling the RNG. The RNG continues to generate new numbers even while the reels are spinning.

Old machines may have locked in the result for a spin as soon as you dropped in a coin, but the standard for new machines is to lock in the result at the last possible moment--when you pull the handle or press the spin button.

Best of luck in and out of the casinos,
John

John,

So, if Keno numbers are drawn at random, I could hit 7 out of 7 and change my numbers and hit 7 out of 7 again on the next turn?

Paul

Dear Paul,

Yes, you could hit 7 out of 7 and change numbers and hit 7 out of 7 again. You could also play the same numbers and hit 7 out of 7 again.

As you said, the numbers are drawn at random.

Best of luck in and out of the casinos,
John

On the multi-denomination video slots, specifically the EZ Play machines, are there multiple settings for the RNG or is there more than one RNG for each denomination?

J.

Dear J.,

There is only one RNG needed in the multi-denomination machines.

Why would a machine need more than one RNG? I assume you're thinking that the RNG is related to the long-term payback of a game.

The only thing the RNG does is generate a stream of numbers that appear to be chosen at random. The RNG has nothing to do with the long-term payback of a game. On a slot game, the layout of the virtual reels determines the long-term payback. On a video poker game, the paytable determines the long-term payback.

The RNG function is identical for an 89% payback Double Diamond and for a 99% payback Double Diamond.

Best of luck in and out of the casinos,
John

On your response to Donna, who was asking about game room machines versus slots, you answered that there is a secondary decision that determines the outcome.

What is that decision that you are taling about?

Thanks,
Al

Dear Al,

Donna asked about Cherry Master machines in particular. On these machines, the stop button can actually be used to stop a reel on a particular symbol--at least according to players who claim to be able to do it--but the program running the machine will alter the symbol if the machine has paid out too much. The secondary decision is the algorithm that changes a symbol when the machines has paid out too much.

Best of luck in and out of the casinos,
John

Hi, John,

Ted

Dear Ted,

I think your message got a bit garbled somehow, but I'll do my best.

RNGS - The RNG, Random Number Generator, is a special function in the machine that generates a series of numbers. The computer program running the machine uses these numbers to determine which symbols land on the payline or which cards are dealt.

IGTS - IGT, International Game Technology, is the largest slot manufacturer in the United States and, if I'm not mistaken, the world.

STYW - I don't know what these letters could stand for. It's not an acronym with which I'm familiar.

Best of luck in and out of the casinos,
John

Send your slot and video poker questions to John Robison, Slot Expert, at slotexpert@comcast.net. Because of the volume of mail I receive, I regret that I can't send a reply to every question. Also be advised that it may take two or more months for your question to appear in my column.

John Robison

John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

#### Books by John Robison:

The Slot Expert's Guide to Playing Slots
John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

#### Books by John Robison:

The Slot Expert's Guide to Playing Slots