Information Technology Reference
In-Depth Information
case of an open standard winning against a closed system was Betamax video which was a
closed standard produced by Sony, up against VHS which was an open standard. VHS was
the inferior technology, but won because there were more companies willing to adopt it.
The days of having a single computer bus for internal and external connections are a
long way off (if ever), as there will always be some peripherals that need to transmit data in
a certain way that differs from other peripheral. Also standard technology always tends to
win over newer, faster technology. Few companies can now define new standards on their
own.
Before we start to look at the technology behind computer busses, here is my All-Time
Best Busses (in order of their current and future usefulness).
TOP BUSSES OF ALL-TIME AWARD
1.
PCI bus
. An excellent internal bus that provides the backbone to most modern PCs. It
has been a complete success, and provides for many modern enhancements, such as
plug-and-play technology, steerable interrupts, and so on. In its acceptance speech
for Best Bus of All-Time it would thank the VL-local bus for starting the trend toward
local bus technology. The VL-local bus held-the-fort for a short time, and gave a
short-term fix for high-speed graphics transfers, but Intel busily developed a proper
bus which could support other high-speed devices. With local bus technology, low-
speed devices were pushed away from the processor, and can only communicate with
it over a bridge. A worthy champion that is the bedrock of modern computing. It even
has a few trump cards yet to play (including increasing its transfer rate, integration
with the AGP port, and increasing its data bus size).
2.
SCSI bus
. The most general-purpose of the external busses and in many respects as
great as the PCI bus, but it looses out to the PCI bus in that it is not used in as many
computers. It provides an easy method of connecting external devices in a daisy-chain
connection. New standards for the SCSI bus support fast transfer rates (over
40 MB/s), and allow up to 15 internal or external devices to be connected.
3.
USB
. An external bus which shows great potential in the way that it integrates many
of the low and medium bit rate devices onto a single bus system. New standards for
USB are trying to also integrate high bit rate devices. It supports hot plug-and-play,
which allows users to connect and disconnect peripherals from the bus, while the
computer is still on.
4.
AGP port
. The PCI, SCSI and USB busses are a long-way out in front to the other
busses, and the forth place in the table goes to AGP port which overcomes the last
great problem area of the PC: the graphics adaptor. AGP provides for fast transfer
rates using the PCI bus as a foundation, and allows the PC to use local memory for
graphics transfers.
5.
PCMCIA
. A long way behind in fifth place comes the PCMCIA bus, which is an ex-
ternal bus that provides for easy upgrades on notebook technology. It highlights how
small and compact interface devices can be. Typical additions are modem and net-
work adaptors. Its future will depend on how the USB bus is used in the future.
And let's not forget the busses which have helped us to get to this point. We may call them
legacy busses, but they have allowed us to get to where we are now, and still provide a useful
function. Thus, the awards for the Most Helpful Busses of the Past (in order of their previous
usefulness) are given next.
