What is the IPO model?

Data processing by computers or humans generally always follow the same sequence of stages: input, process and output (IPO). For this reason, the universally applicable IPO model is used in connection with electronic data processing. This also describes how computers function and operate.

What does the IPO model stand for?

The abbreviation “IPO” is derived from the first letters of the words input, process and output:

  1. Data is entered into processing units such as computers via input devices.
  2. The data is processed according to predefined rules.
  3. The processed data is displayed or output for users via various display or output devices.

The IPO model (sometimes knows as the IPO principle) describes the basic sequence of data processing and is regarded as an important basic pattern of EDP (Electronic Data Processing). It does not matter whether the data is entered and processed by a computer or a human being. What is important is that the sequence for data processing remains the same. The IPO approach describes systems holistically as well as in parts. This means, for example, that a computer system first receives an input as a whole in order to process and output it in certain subareas of the system.

Why is the IPO model important?

Some may claim that the IPO model only describes what is already obvious. However, from a hardware and software development point of view, it is actually an important guideline. Only when the basic structures of data processing correspond to the IPO model can it be assumed that input, process and output will be aligned to the desired mode of operation and no errors will occur.

In the following section, we’ll explain the significance of the IPO model when it comes to hardware and software development:


When developing hardware, it must be clear which types of input signals the hardware should process. This is because the type of input signal determines which devices should be used for the input. The processing units needed are determined by how the processing should take place. The output devices used for the display or output depend on which actions are desired after the input.


Software development also follows the IPO model. A program must be developed in advance with the input data in mind, in order to understand what is supposed to be done with the data. For example, in text or system programs, input, data process and output occur differently than in a design program or multimedia player. Depending on the input command, other units and output devices may need to be controlled. Programming paradigms and algorithms that are used in the development of software also rely on the IPO model.

How does input, process and output work?

As a universal guideline, the sequence and flow of data processing according to the IPO model can be explained like this:

Input (“I”)

The input of data takes place in the form of a command or instruction given to the device or system. Input can be made via various input devices as required. These include:

  • Computer keyboard
  • Mouse
  • Microphone
  • Touchscreen
  • Touchpad
  • Scanner
  • Webcam
  • Eye control
  • On-screen keyboard
  • Game controller/joystick

Input devices are used to enter commands and data in various forms and ways. This includes letters, numbers, clicks, symbols, Windows shortcuts, voice commands, touch commands, visual data or scans of documents. Depending on the device and program you are working with, the data is processed differently.

Process (“P”)

The processing or calculation of input data is performed by units designed for this purpose. The most important of these are the processor (CPU), the RAM (main memory) and the graphics card (GPU). The most important unit for processing is the branch of the processor and RAM. Here the output is calculated, and the input command is implemented, while data is stored and cached simultaneously.

Hard disks, RAM, cloud storage, DVDs and USB sticks are used for storage. It should be noted, however, that memory is not considered a processing unit, but has a separate position in the IPO sequence. The algorithm determines which output devices are controlled and which data is processed.

Output (“O”)

In order to output the processed data as required, computers or electronic devices have corresponding output units. These ensure that processed data is displayed on a monitor/screen or output via, for example, speakers, a printer, projector or headphones. This means that the movement of the mouse pointer on the monitor is just as much an output according to the IPO model as letters being typed on the screen or documents being printed.

When is the IPO model used?

Since it is a universal guideline, the IPO model can basically be applied to any situation where input signals should lead to results. The best example are the “input devices” of the human body, be it eyes, ears, nose, mouth or skin. On the one hand, we take in external signals passively via smells, sounds and the visible environment, and on the other hand, we take them in actively by reading, watching a movie, listening to music or enjoying our favorite food. Signals are processed and results produced via our senses and processing units such as the brain, organs, bones, muscles and tendons. These include images, colors, tastes, meanings, a smell or conversations.

When developing functional hardware and software, the IPO model plays a decisive role, especially from the point of view of troubleshooting and performance optimization. The model specifies test sequences that indicate when an input signal does not result in the desired output. This means that errors or incompatibilities in input devices or output devices as well as deficiencies in processing units can be identified and rectified. In this way it can also be determined, for example, whether data processing in processors is to take place simultaneously over several cores by multithreading or hyperthreading and which areas of the kernel are used.

Examples of the IPO model from data processing

Examples of the IPO model can be found in basically every data input on your PC, smartphone, tablet, printer, scanner or Bluetooth device. For example, if you enter a word via the keyboard, the signals from the keyboard are displayed on the monitor as a word via processing units such as the CPU, RAM and word processors. In turn, if you click on a video link, the browser calls up the corresponding website, the computer’s audio devices start audio playback, and the video is displayed on the monitor.

The same applies when printing a document. You select the format, the printing color and the number of copies, then start the printing process and at the end, you hold the printed documents in your hand. Every machine that fulfills a certain function is basically applying the IPO model. This could be an ATM for dispensing cash or displaying your account balance, a scanner for scanning documents, a game console hooked up to a screen with game controllers or a music system with speakers.


The IPO model represents an important guideline for guaranteeing seamless, efficient data processing. It ensures that errors between input and output are excluded or identified and makes it possible to make data processing processes as continuous and resource efficient as possible.

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