The MPU is the brains of a modern slot machine. The MPU controls all the data, and tells all the other components what to do. If a component malfunctions then the MPU will report this to the display. (The MPU can be thought of as a boss giving orders to his workers. If the workers are not doing their job then he will report them to you).
The way the MPU reports bad components is by going into what is called a TILT. When it does this, the game will not be playable and will show the tilts error code on the display.
Often the MPU tilt codes can be somewhat ambiguous but don’t worry they are not hard to figure out.
The MPU needs a way to talk with the other components. It does this through a component called the MOTHERBOARD. A motherboard is the place all the components can plug into and then sent to the MPU.
There are many small traces running across the motherboard. All of which go to a plug that the MPU plugs into. Most often the MPU sits on a metal tray and slides in and out to connect to the motherboard. The motherboard doesn’t have many electronic components on it. It is mainly an interface between the MPU and the other components.
When I talk of other components these are things like the buttons, hopper, bill validator and so on. All these components can be broken down into two categories INPUT and OUTPUT.
Input components are things like buttons, handle, bill validator and so on. Output components are components like the hopper and display. There are many more input and output components of a slot machine.
The main thing to remember is all the components of a slot machine are ether input or output devices. The MPU waits for an input so that it can take action and give an output.
For example when you put a bill into the bill validator this is an input. The bill validator checks the bill to see if it’s valid and what denomination it is. Once the bill is accepted the bill validator sends a signal to the MPU. The MPU receives this signal and then sends an output to the display of how many credits to show.