The Computeris a modular equipment. You can add or remove the peripheral devices as and when you want. However, this also throws up some challenges. Each device added to the system must be configured in order that it functions properly. It must be assigned a unique IRQ, DMA and Input/ output resources.

In early days of the PC, the devices were configured manually by means of jumpers on the peripherals and inside the adapters and the motherboard. This would cause problems in assigning unique resources and overlapping of the resources would inevitably occur. Hence, adding new devices into the PC system used to be a trial and error and time consuming job for the technicians and the end-users.

Plug and Play is the technology that allows for the automatic configuration of the devices. The Plug and Play technology simplifies the task of configuring the devices connected to the computer, thus relieving the technicians and the end users from configuring the devices all by themselves. Hence, an understanding of the Plug and Play configuration technology can go a long way in making the task of those involved in repairing or assembling their computers much more easy.

The three components involved in making a system plug and play are the Pnp devices, the Pnp Bios and the Pnp operating system. We will take a look at these one by one.

Pnp Devices :

You need to fit several peripheral devices into your computer. These devices must be Plug and Play. If they are Plug and Play devices only then they will be recognized automatically by your system. Nowadays, almost all the peripheral devices you purchase are plug and play devices.

Pnp BIOS.

If you connect Pnp devices to your PC but the version of BIOS in your PC does not support Pnp, then it would be no use connecting Pnp devices. There must be a Plug and Play BIOS in the system in order to connect Plug and Play devices. The Plug and Play BIOS is required in order to initiate the Pnp devices during the POST and transfer control to the operating system.

Pnp operating system.

The windows operating system is a Plug and Play operating system. When the BIOS detects and initializes the Pnp devices  attached to your computer, the control gets transferred to the operating system. The Pnp operating system loads the device drivers needed to operate the proprietary devices.

How does the Pnp system operate?
 
The Pnp devices, the Pnp BIOS and the Pnp Operating system work in cooperation for the Pnp system. The BIOS in the PC performs certain initialization and configuration of the Pnp devices. The BIOS passes control to the Pnp Operating System transferring certain information about the devices. The Operating system identifies the different resources such as the IRQ, DMA and the I/O addresses required by the attached devices and configures the devices accordingly. The Operating system identifies each of the devices and loads the device drivers for the devices and transfers the information of the resources allocated to the device drivers.

How to manage the Plug and Play Devices?

By ‘Managing the Plug and Play Devices’ is meant the installation, updating, removal and disablement of the Plug and Play devices. The operating System such as the Windows Xp provides the necessary tools to install, update, remove and disable the Plug and Play devices.

Installing the Plug and Play devices is simple. You can just insert the adapter board into the expansion slot, connect the device to the adapter and turn on your Pc. The device gets automatically installed into your system : it gets detected automatically, the resources are assigned to the device automatically and the device driver gets installed automatically. In case your PC does not have the device driver support for your peripheral device than the operating system asks you to insert the disk provided by the manufacturer of the device. The device driver is then loaded into the PC from the disk provided by the manufacturer of the device.

Sometimes it may be necessary to update the device drivers. One such case is when the  manufacturer improves upon the existing device driver and announces an update. The procedure to update the device driver in your system is as follows :

Step 1.

In Windows Xp go to the control panel and click on the systems icon. Click on the Hardware tab. Click on the Device Manager. You will see the list of devices connected to your system. You can check to see whether the devices are being recognized and they are properly installed or not.

Step 2.

Insert the new CD in the CDROM drive containing the updated version of the device driver supplied by the manufacturer. Click on the update driver icon. This will display the dialog box to update the driver. Click next and the device driver will be updated.

During troubleshooting, it might become necessary for you to disable or remove the peripheral device from the PC, to check whether the PC runs properly when the device is disabled or removed. When you Physically remove the Plug and Play device from the PC the Pnp operating system will automatically remove the device driver and, thereby , remove the device from the system.

For disabling the peripheral device without removing the device physically follow the following procedure. Go to Control Panel. Click on the System icon. Click on the hardware tab. A list of devices attached to your system is displayed. Click on the device you wish to disable and click on properties icon in the tool bar. Click on the option to disable the device.

If you wish to assemble or troubleshoot your PC, understanding Plug and Play is very important. Plug and Play removes the uncertainties accompanying the installation, updating and disabling of devices in the PC. It makes the task of device management easy and automatic for the technicians and the end-users.