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A system flowchart is a visual representation of processes, decisions, inputs and outputs that together form a system.

What is a system flowchart?

To illustrate this, symbols are used. They are connected together to show what happens to data and where it goes.

Note that system flow charts are very similar to data flow charts. Data flow charts do not include decisions, they just show the path that data takes, where it is held, processed, and then output.

Using system flowchart ideas

This system flowchart is a diagram for a 'cruise control' for a car. The cruise control keeps the car at a steady speed that has been set by the driver.

The flowchart shows what the outcome is if the car is going too fast or too slow. The system is designed to add fuel, or take it away and so keep the car's speed constant. The output (the car's new speed) is then fed back into the system via the speed sensor.

Other examples of uses for system diagrams include:

• aircraft control
• central heating
• automatic washing machines
• booking systems for airlines

Input and output

For the system to work there is an input and an output. The process is taking the input and doing something with it - modifying it in some way - and producing an output.

In a computer system the processing will be done by a microprocessor of some kind.

Feedback is the output fed back to the input. The cruise control flowchart is an example of negative feedback because the speed is always kept at the same value. Positive feedback would push the speed away from the desired value.

Inputs

Here are some examples of inputs:

• keyboard
• mouse
• microphone
• scanner
• camera
• pressure sensor
• temperature sensor
• magnetic sensor
• moisture sensor
• light sensor

Outputs

Here are some examples of outputs:

• printers
• speakers
• motors
• monitors
• heaters
• electromagnets
• bulbs/LEDs