In 1977, five-wire resistive technology was developed and patented – the same type used by the Nintendo DS today. The user can interact with the display's content with either a plastic stylus or their fingers. Contact based in the corners and one in the centre estimate the pressure of a touch, based on calculations from the resistances. Other applications of this technology include PDAs, and mobile phones such as Apple's iPhone. Resistive touch-screen's cousin, infrared touch-screen, has the most durable surface, however, and is used in various military applications.
With the appearance of a set of scales from the bathroom of Buck Rogers, the Wii Fit balance board contains four pressure sensors accurately to detect fine changes in weight distribution. This allows the user to control the game by moving the body and leaning. So far, Wii Fit games include yoga; ski-jumping; tight-rope walking; and – perhaps slightly depressingly for the obsessive computer enthusiast – measuring Body Mass Index. Future titles such as Jillian Michaels' Fitness Ultimatum 2009 could potentially do wonders for the average gamer's physical health.
Developed for the PlayStation 2, Sony's Eye Toy is a camera with a built-in microphone that sits on top of the television, allowing players to interact with the game by detecting sound and motion. Sony weren't the first to come up with the concept – Nintendo's Game Boy and Sega's Dreamcast both had cameras before them – but improved processing capabilities meant that the PS2 was able to have a much better go at it, and an updated version is also available for the PS3. Future developments will include users being able to draw their own interactive landscapes and environments.
Through the use of accelerometer and optical-sensor technology, gamers can interact with and manipulate items on the screen using movement and pointing. Hackers have shown great interest in the technology, using the Wiimote (among other Wii products) for other applications, known collectively as Wii Homebrew. Companies are looking into reprogramming the Wiimotes for business applications, and there's already been an interactive whiteboard created using the one-handed controllers.