Plug and play

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Plug and Play (English for "plug in and play" or "connect and get started"), also known as Plug & Play ( PnP for short ), is a term from the field of computer technology used to describe the properties of a computer , new devices - mostly peripheral devices - without having to install device drivers or make settings afterwards .

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There are several names and variations of the term that describe similar properties, such as hot-plug . The term Plug and Play is usually associated with Microsoft , which first used this name for its Windows 95 product . Since the process was technically immature at the beginning, the derisive term “Plug and Pray” (“plug in and pray”) was also used and is still used today.

Plug and play only works if it is supported by both hardware and software . The hardware usually generates an identification code so that the software can correctly recognize the device. The Apple Desktop Bus (ADB), which has now been replaced by USB , used a four- bit code for this purpose. Most systems now use longer codes of various types in order to be able to transmit more information such as device names or serial numbers.

On the hardware side, it is required that the computer bus must recognize changes in the configuration when devices are added or removed. With the introduction of more modern systems - particularly USB and FireWire - this very ability was introduced into computer bus technology.

After all, the operating system must be able to handle the changes when devices are plugged in or unplugged. This means that it triggers an interrupt (see interrupt request) on the system bus, which displays the changes and then determines what has been changed. With older bus designs, all system information had to be read out to find out what has changed. When using multiple devices, this can take a relatively long time. Modern systems are therefore developed in such a way that the search for changes takes as little time as possible. In the case of USB, a hub system is used for this (as well as for other purposes) .

When a configuration change is detected, the operating system reads the information provided by the new device to identify it. Next, it has to load the drivers required for the device during operation, if this has not already been done.