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

VESA VL Bus 1 Plug and Play (PnP)

PCI stands for Peripheral Component Interconnect. Originally developed by Intel in 1993, it was and is the current popular data transfer bus. PCI moves data at either 32 or 64 bits at a rated transfer speed of 33 MHz and so is compatible with Pentium processor technology. The PCI bus introduced several new improvements over prior bus designs:

Burst Mode can transfer information where after an initial address is provided multiple sets of data can be transmitted in a row without having to re-establish the address location.

Bus Mastering, which provides for improved performance. Bus mastering is the capability of devices on the PCI bus to take control of the bus and conduct data transfers directly. The PCI bus is the first bus to popularize bus mastering because there are now operating systems and software that are capable of taking advantage of it.

High Bandwidth Options, which are PCI, bus specifications calling for expandability to 64 bits and 66 MHz speed. This will quadruple bandwidth. While the 64-bit PCI bus has yet to be commonly implemented on the PC and the speed is currently limited to 33 MHz in most PC designs, most likely for compatibility reasons. The mainstream PCI bus may be limited to 32 bits and 33 MHz for some time to come.

PCI-X is a newer, high-speed implementation of the traditional PCI bus supporting data transfer speeds of 66, 133, 266 and even 533 Mega Transfer/sec (MTS). This is 32 times faster than the original PCI implementation. PCI-X is built to use the same protocols, signals, and connectors as traditional PCI. PCI-X 2.0 features include up to quadruple bandwidth of the first PCI-X release, full backward compatibility with PCI, supports 10 GB Ethernet and Fiber Channel, and Remote Access Server support.

VESA VL Bus 1 Plug and Play (PnP)