Understanding The Speed Of New PCI Express Data Bus
by Otis Cooper
The personal computer is constantly changing with such component upgrades for
memory, CPU speed and hard drive capacity. And the video display is no exception.
The video display consist of a Graphics Card, Monitor, and the Bus. If you're
wondering what the heck is a Bus in any video display, its the data path along
which data moves into, out of, and inside the computer.
This data is sent from the motherboard and central processing unit, to the
graphics card, travels along the data path or Bus, to the Monitor where our eyes
can see it. The data Bus is partly responsible for our clear and fast the
graphics of our favorite games are displayed.
It does not matter how fast the CPU chip or graphics card can send data if the
Bus becomes too small and prevents the data from traveling fast. This causes a
bottleneck of data when the graphics card sends data faster then the Bus can
allow it to travel.
The first Bus was introduced by IBM or International Business Machines and was
called the ISA. The Industry Standard Architecture Bus was slow and weak since
it sent data at just 4MHz. But it was matched with the CPU chip of that day.
The average CPU speed during this time was around 4.77MHz. This bus came in 1981
and IBM created a faster bus soon after with a 16 bit bus with a CPU speed of 8
to 10 MHz three years later.
By this time many other computer makers were building Computers using the IBM
design and IBM quickly responded to the competition by making a proprietary bus
called the MCA or Micro Channel Architecture. When IBM built proprietary Buses
they mean they built hardware or software, in this case Buses, owned and
controlled by a single individual or organization.
The Bus technology came about in the following order.
1983 IBM introduced the ISA Bus and in 1984 the faster 16 bit ISA Bus arrived.
Then in 1987 the 32 bit MCA Bus showed up. And in 1988 Compaq and other PC
makers released the 32 bit EISA or Extended Industry Standard Architecture bus.
1993 brought us the Video Electronics Standards Association or the VESA Bus.
This year also allowed the release of the PCI or Personal Computer Interconnect Bus.
And in 1996 came the AGP or the Advanced Graphics Port while 1998 brought us the
AGP 2.0 and in 2002 came the ,you got it, the AGP 3.0 data bus.
Finally in 2005 Intel and AMD introduced computers running at speeds of 4Gigabytes
or more. At these speeds the AGP port presented at slowdown for the data. So the
folks at Intel put their heads together and came up with the PCIe. The Personal
Computer Interconnect Express. The bus is like the PCI but uses a serial port
whereas the PCI use parallel ports.