How Pokies Really Work

There are a lot of myths and misinformation when it comes to how pokies work. In this section we show you how they really work. While we are focusing on pokies in this article this is also the way that all video slot machines work so the information applies to any five reel slot machine with a video screen found anywhere in the world.

The Parts

All poker machines are made up of a range of parts. These include external parts and internal parts. Below we list the major parts.


  • Cabinet - This houses the game and comes in a variety of types
  • Video Screen - This is where the game is displayed
  • Buttons - Found under the screen and used to interact with the game
  • Note & Coin Acceptor - Used to insert coins or notes into the machine
  • Top Box & Belly Panel - Used to display game artwork and pay table
  • Coin Tray - Found at the base of the machine. Paid coins collect here


  • Motherboard - A computer component that holds parts such as RAM
  • EPROM (Erasable Programmable Read-Only Memory) - The game logic
  • Interface Card - Connects the EPROM and motherboard to the buttons
  • Meters - Record all game data, pay outs, money in, etc.
  • Cables - Connect the screen, motherboard, buttons, etc.
  • Note Validator - Checks all inserted notes for authenticity
  • Lights - Found behind the top box and belly panel art covers
  • Cash Box - Stores all notes inserted into the machine
  • Hopper - Stores all coins in the machine releases wins to the tray
  • Speakers - Play the game sounds such as the win music
  • Door Alarm - A sound to alert staff to a door on the machine being open

What Happens When You Press Spin

On the right is a diagram showing a simplified example of a poker machine. The virtual reels have been extended out of the screen to show that they continue past the visible screen area.

Pokie Diagram

You will notice that each of the symbol positions has a different number. In our example there are 15 symbols per reel but there can be anywhere from 10 to 1,000's of symbol positions.

While the reel positions have different numbers you will find that there are more lower paying symbols on each reel than higher paying ones. For instance a low paying symbol could be in positions 2, 5, 9 and 11 on reel one.

As soon as you press spin the EPROM randomly selects five numbers - one from each reel. In the example on the right this would have been 6, 30, 38, 51 and 69.

The reels then spin and come to stop on the selected positions. You are then awarded any resulting wins and then have the option to try to double up your win. The games pay back percentage (RTP) is controlled by the symbol positioning through extensive mathematical testing.

One point to note is that the symbol positions never change and that the casino or pub cannot change the payout percentage. For this to be changed a new EPROM must be installed. Each game type can come in a variety of different payout levels.

Online Pokie Games

Online pokies work in exactly the same way with the only real difference being that instead of an EPROM, the game logic and RNG is on a remote server that your game connects to.

When you press spin a message is sent from your computer to this server and the server returns an encrypted set of numbers that resolve to the symbol positions you see on the screen.