[Courses] [Networking] PCI (was: Lesson Two - Purchasing the Right Hardware)

[Hamster]

In the first place, thanks to Sue for pointing out that typing mistake.

Now to answer your "what is PCI question".

In the beginning, hardware manufacturers said "let there be a motherboard"
and lo and behold there was a motherboard. These early motherboards
contained only slots for mounting the CPU, RAM and keyboard. Everything
else; diskdrive controllers, video card, serial and parallel ports had to be
purchased separately and plugged into the motherboard. If you wanted to use
your computer for a specialist purpose, such as controlling manufacturing
equipment or taking sensor readings, you needed to purchase these cards
separately as well. Obviously you needed some sort of standard that allowed
you to purchase all these different cards from different manufacturers yet
have them all fit onto your motherboard (and work).

So they devised a standard that allowed just that. The early standard was
called ISA and stands for Industry Standard Architecture.

Over time as technology improved and things got smaller and faster, many of
the items you once had to buy separately became incorporated onto the
motherboard itself. However the need to be able to expand the capabilities
of your computer by plugging in extra components has never waned. Nowadays
we want to plug in network cards, firewire ports, TV capture cards and all
manner of things. The old ISA bus slowly gave way to a new type of expansion
slot called PCI (Peripheral Component Interconnect) that's basically
smaller, better and faster :-)

The word "bus" simply means "method of transporting data from one part of
the computer to another". There's a bus for everything. Memory bus, disk I/O
bus and expansion slot (PCI or ISA) bus to name a couple.

Even PCI itself has gone under several revisions, I believe the newest
version of the PCI standard is 2.2

So in summary - PCI is the current standard that governs how the expansion
slots on your motherboard work and what they look like. These expansion
slots enable you to increase the functionality of your computer by plugging
in extra features.

I've got a thing for illustrations at the moment, so if you look at

http://linux.invisiblepixels.org/writings/networkcourse/img/mobo.jpg

there's a picture of an Pentium 2 motherboard. The 3 long black slots on the
far right are ISA slots, then you'll see 4 white PCI slots to the left, then
left again next to that is one brown AGP (accelerated graphics port) slot.

Just out of interest, there are two other types of slots/buses also
associated with PC's. One is called MCA (micro channel architecture) and was
developed by IBM, and another called EISA (developed by nine of IBM's
competitors). Neither of these buses ever caught on as they were upstaged by
PCI.

Hope this helped a bit!?

Hamster