PCI EXPRESS

PCI EXPRESS

PCI Express, officially abbreviated as PCI-E or PCIe, is a computer expansion card interface format introduced by Intel in 2004. PCI Express was designed to replace the general-purpose PCI expansion bus, the high-end PCI-X bus and the AGP graphics card interface. In PCI 1.1 (currently the most common version) each lane sends information at a rate of 250 MB/s (250 million bytes per second) in each direction. PCIe 2.0 doubles this, emerging in late 2007, and is found on newer systems such as those based around the Intel X38 or AMD 780G chipsets.

Each PCIe slot carries either one, two, four, eight, sixteen or thirty-two lanes of data between the motherboard and the card. Lane counts are written with an x prefix e.g. x1 for a single-lane card and x16 for a sixteen-lane card. Thirty-two lanes of 250 MB/s (PCIe 1.1) gives a maximum transfer rate of 8 GB/s (250 MB/s x 32, i.e., 8 billion bytes per second) in each direction. However the largest size in common use for PCIe 1.1 is x16, giving a transfer rate of 4 GB/s (250 MB/s x 16) in each direction. Putting this into perspective, a single lane for PCIe 1.1 has nearly twice the data rate of normal PCI, a

four-lane slot has a transfer rate comparable to the fastest version of PCI-X 1.0, and an eight-lane slot has a transfer rate comparable to the fastest version of AGP.

AGP EXPANSION SLOTS

It stands for Accelerated Graphics Port,an interface specification developed by Intel Corporation. AGP is based on PCI, but is designed especially for the throughput demands of 3-D graphics. Rather than using the PCI bus for graphics data, AGP introduces a dedicated point-to-point channel so that the graphics controller can directly access main memory. The AGP channel is 32 bits wide and runs at 66 MHz. This translates into a total bandwidth of 266 MBps; as opposed to the PCI bandwidth of 133 MBps. AGP also supports two optional faster modes, with throughputs of 533 MBps and 1.07 GBps. In addition, AGP allows 3-D textures to be stored in main memory rather than video memory. AGP has a few important system requirements as:

• The chipset must support AGP.

• The motherboard must be equipped with an AGP bus slot or must have an integrated AGP graphics system.

• The operating system must be the OSR 2.1 version of Windows 95, Windows 98 or Windows NT 4.0. And currently, many professional Macintoshes support AGP

PCMCIA

PCMCIA-stands for Personal Computer Memory Card International Association. The bus was originally designed to provide a way of expanding the memory in a small, handheld computer. The PCMCIA was organized to provide a standard way of expanding portable computers. The PCMCIA bus has been recently renamed as PC card to make it easier to pronounce. Although it isprimarily used in portable computers, there is PC card bus adapters for desktop PCs. It was designed to be a universal expansion bus that could accommodate any device.

There are three major types of PC cards (and slots) in use today. Each has different type uses and physical characteristics they are called Type I-commonly used for memory cards, Type II-used for modems and LAN adapters, and Type III-most common application is for the PC card hard disks.

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