CertiGuide to A+ (A+ 4 Real)  9  Chapter 8: Motherboards

PCI 1 PCI Steering

Most people today are used to Plug and Play technology where the operating system automatically detects a newly installed device and runs an Add New Hardware Wizard. Prior to 1996, this technology was not available and the computer and operating system were not automatically aware of changes to their hardware configuration. For proper operation devices needed to be configured manually, usually by jumpers or dip switches.

Plug and Play is actually a combination of interactive features in computers, devices, and operating systems. The technology ideally detects the presence of a new device when the PC boots self-tests and the operating system loads. Then the operating system (typically Windows) will open an Add Hardware Wizard and guide the user in a step-by-step process of loading the drivers (which usually accompany the actual device on a CD-ROM disc) and enabling the device for use. Windows XP sometimes does not provide the user with the option of loading the drivers that come with the device and will load Windows drivers instead. Some devices function better with their own drivers and the device will usually come with instructions on how to “convince” XP to use the drivers stored on the disc.

The computer, motherboard, and the device must all be PnP compliant. All modern PCs support PnP but the occasional legacy machine or device may still require manual configuration. In addition, the BIOS must support PnP for the devices involved. Older BIOS may not support PnP for a particular device. The solution to this problem would be to “flash” or upgrade the BIOS to the most recent version.

I am sure you have heard of resource conflicts between devices installed on a PC. It used to be that technicians had to configure manually devices for I/O, IRQ, and DMA assignments. PnP handles those assignments the vast majority of the time so it is rarely an issue today. In addition, it is possible using PCI v 2.1 for devices to actually share IRQ assignments (please refer to the section of this text that discusses device resource assignments for details). When all is said and done, PnP technology has made the life for the A+ technician remarkably easier in the performance of routine device installation.

PCI 1 PCI Steering