With more than 30 times the bandwidth of the popular
1.1 peripheral standard,
FireWire 400 has been the gold standard for high-speed data
transfer. Apple was the first computer manufacturer to include
across its entire product line. And now Apple has upped the ante yet again,
effectively doubling data throughput with its implementation of the IEEE 1394b
FireWire 400 vs. USB 1.x
have both found their place in the computer and consumer electronics industries.
the technology of choice for most computer mice, keyboards and other lower
bandwidth input devices.
FireWire, with its higher bandwidth, longer distances and
much higher-powered bus — is more suitable for such applications as digital
video (DV), professional audio, hard drives, high-end digital still cameras and
home entertainment devices.
How fast is 1394?
The 1394 standard defines three signaling rates which, in precise terms, are:
98.304, 196.608 and 393.216 Mbits/s (megabits per second). These rates are
referred to in the 1394 standard as S100, S200 and S400. The 1394b specification
(finalized in early 2002) expands the standard to include 800 and 1,200 Mbits/s
speeds. You can mix and match devices of different speeds on the same bus. Using
"isochronous" data transmission, even the S100 implementation supports two
simultaneous channels of 30fps (frames per second) broadcast-quality video along
with stereo audio.
How does 1394 compare to SCSI?
The SCSI bus requires that devices be serially daisy-chained together, with each
device having a non-conflicting, pre-assigned address and that the final SCSI
device be terminated. There is a limit of seven devices on a SCSI chain. In
contrast, 1394 devices can be connected in multiple configurations. These can
include a star or tree pattern with its own daisy chain branches. Device
terminators are not required. And 1394 addressing, unlike SCSI, is done
dynamically; there is no need for address pre-assignment. Plus, 1394 allows up
to 1,023 buses to be bridged together.
How does 1394 compare to Ethernet?
1394 multiplexes (combines) a variety of different types of digital signals,
including video, audio, MIDI and device control commands, on two twisted-pair
conductors (similar to that of 10base-T Ethernet). This ability to easily
multiplex or combine different signal types distinguishes 1394 from other
systems which transmit only a single signal type.
Ethernet, for example, is typically used in data networks and requires special
protocols (presently implemented only in proprietary multimedia networking
systems) to transmit real-time, high-quality audio and video.
In comparison, 1394 is much more flexible in its accommodation of different data
types and topologies than Ethernet and other alternative networking systems.
1394 uses a "fairness" arbitration approach to assure that all devices that have
information to transmit get a chance to use the bus. 1394 protocols also include
device-specific commands to start and stop camcorders, VCRs and other tasks.
Standard Ethernet does not provide these important features.
What is hot swapping?
Hot swapping is the connection and disconnection of computer peripherals or
other components while a system is turned on, without interrupting system
operation. 1394 enables hot swapping.
- Strip the cables Jacket back one full inch.
- Untwist the wires back to within 1/8" of the jacket.
- Arrange the wires in the order in which you want to crimp them. You can
choose from either the 568-A or 568-B wiring methods, however the 568-B is
the most commonly used.
- Grasp the wires firmly, between your thumb and forefinger, flatten them,
and even wiggle them a bit, to take out the curliness, (concentrate your
efforts on the bottom 1/2") the wires must lay flat and together, aligned as
close as possible.
- While holding the wires firmly, cut off the the wires 1/2" from the
cables jacket (Cut the wires with some sharp
or even high quality scissors, avoid wire cutters that flatten the ends of
the wires insulating material, this makes stuffing the wires very
- Stuff the wires into the connector, making sure the wires stay lined up.
Push moderately hard to assure that all of the wires have reached the end of
the connector. Be sure that the cable jacket goes into the back of the
connector by about 3/16".
- Place the connector into a
and squeeze hard so that the handle reaches it's full swing.
- Repeat the process on the other end. For a straight through cable, use
the same wiring.
- Use a cable
tester to test for proper continuity
How to wire a CAT5
(EIA 568-B*) Cable.
How to wire a CAT5 (EIA 568-A*) Cable.
The only real difference between 568A and 568B is that
the White/Orange-Orange/White and White/Green-Green/White pairs are swapped.
How to wire a "Crossover" Cable. (EIA 568-B*)
USOC crossover cables are like this:
The Universal Serial Bus or
cable was developed around the idea that users should be able to run multiple
peripherals on their computers without the hassle of physically installing
boards, manually allocating system resources, individually configuring devices,
and powering the computer up and down every time equipment needs change. With
USB cable, up to 127 individual peripheral devices can be connected to a host
computer using a single interface and a system of USB hubs. (See below for a
diagram of a typical USB system.) Attaching a USB peripheral to your computer is
as easy as plugging headphones into your Walkman. USB devices are automatically
recognized and configured. They can draw power directly from the system, from an
attached self-powered hub, or be connected to their own power supply.
USB Cable Features
provides two-way communication between the PC and peripheral devices, making it
ideal for many I/O applications. Multiple devices can connect to a system using
a series of USB hubs and repeaters. A single USB interface is attached to the
motherboard. A Root Hub with up to seven additional ports can be integrated into
the main interface, or it can be externally connected with a cable. Each of the
seven hubs on the Root Hub can in turn be connected to seven hubs, etc. to a
maximum of seven tiers and 127 ports. A unique feature of USB is that a
peripheral device can have a hub built into it. This type of peripheral, called
"compound devices," are comprised of a function device and one or more hubs. For
example, a USB keyboard can contain an additional USB port for a USB mouse.
is generally described as having a tiered star topology, however each device
communicates with the host as if it had its own connection. This means that
communication from the host centers around a set of hubs/devices, each of which
in-turn serves as the center for another set of hubs/devices, etc. However, the
hubs are transparent to the software and the devices are addressed individually.
Cables are used to create point-to-point connections between devices and USB
ports, or to connect one USB hub to another. The maximum cable length is five
meters long. However, a repeater hub may be used to extend the distance between
the peripheral and the host. There are also special USB repeaters that can be
used to extend the connection even further.
USB Cables and Ports
The Root USB
Hub is connected directly to the USB Host, and from there everything is done
with cables. Two types of USB cables can be used with USB devices: Series A and
Series B. Series B cables are limited to 3 meters in length and are for use with
low-speed (1.5 Mbps) USB peripherals such as keyboards and mice. The UTP cable
has a pair of 28 AWG wire stranded copper for data and one pair 20-28 AWG for
The Series A connector is for use with high speed (12 Mbps) devices, and can
be up to 5 meters long. The more common of the two, it consists of one pair
20-28 AWG wire for power (VBUS is typically +5V at the source) and one 28 AWG
twisted wire pair for data. The connector has a shielded housing, making it STP
USB Cable Power Management
One special feature of
USB systems is that they can directly supply power to the
peripherals and the hubs attached to them. It can also regulate power usage for
peripherals that use independent power sources. USB devices are classified based
on the amount of power they supply or require. Low Bus Power devices take all
their power from the bus, but no more than 100mA at a time. High bus-powered
devices also take all their power from the bus, but can draw up to 500mA at a
time. Self-powered devices use an external power supply, but can draw up to 1mA
from the host if necessary--such as in the case of a power failure.
Hubs can also be low, high or self powered. Power flows downstream in a
system, which means that a self-powered hub can be used to power high- and
low-powered peripheral devices located further down in the network. This power
arrangement has both advantages and disadvantages. For desktop systems where
power is not a problem, it is extremely convenient not to have to use a separate
outlet for each peripheral connected to the PC. In notebooks where battery
longevity is often a problem, it might be more advantageous to use peripheral
devices that have their own power source.
Specification 1.1 was designed for low to medium speed applications running at
less then 12 Mbits/sec. As such it is not suited for high-end data transfer such
as high-speed back-ups to hard disks or CDs , high resolution color printing and
interactive gaming. The recently released USB Specification 2.0 aims to upgrade
the bus for high performance applications. The main difference between
Specification 1.1 and 2.0 is that the latter provides for data transfer rates up
to 480 Mbits/sec.
2.0 is fully backward compatible with all older USB devices. It merely adds
another device class--"high speed device." The USB host controller determines
the type of devices attached to it, and then treats them accordingly. In fact, a
high-speed USB hub can be used for both high, full (12Mbps) and low (1.5Mbps)
speed devices at the same time.
adapters will remain USB 1.1 devices, as even the fastest serial communication
is limited to 10Mbps--well within the range of a full speed device.
USB for Data Communication
For low to medium speed data communication applications
Specification 1.1 provides a clear usability advantage older bus types. USB
peripherals are both Plug and Play and Hot Swappable devices. Further, USB cable
is flexible enough to incorporate up to 127 individual devices into a single
system using only one interface. And, unlike PCMCIA cards, where the board
itself is subject to considerable wear from multiple insertions and extractions,
USB devices use a connector cable which can be inserted and removed multiple
times without consequence. Because of USB's structure, it can potentially reduce
system downtime considerably.
As a bus option designed for both desktop and portable use,
can bridge the gap between desktop and portable peripherals, provided the new
peripherals are designed in small enough form to be practical for portable
systems, and provided they do not draw too heavily from a laptop's limited
2.0 with its considerably higher speeds rivals both board-level interfaces such
as PCI and other interfaces such as Firewire. In fact, some computer companies
are pushing for a PC standard that will no longer supply slots for plug-in
boards, and will rely completely on USB and Firewire type devices.
major drawback is its inability to implement peripherals designed for older
protocols. As USB popularity increases, it is becoming more likely that a USB
device exists for any given application. However, software applications written
for non-USB peripherals cannot be implemented using USB because of the
difference in communication protocols. Quatech has solved this problem with our
FreedomUSB serial adapters. With Quatech's FreedomUSB Series you can take full
advantage of USB benefits while continuing to use your current serial
peripherals in your existing applications.
A keystone jack
is a female connector used in data communications, particularly local area
networks (LANs). A keystone jack is usually mounted in a
or patch panel.
A keystone plug is the matching male connector, usually attached to the end of a
cable or cord that is inserted into the jack for data communications.
A principal advantage of keystone connectors is their versatility. Several
types of keystone jack
can be mounted on a single
patch panel. They are available in CAT3, CAT5e, and CAT6;
in either shielded or unshielded forms. Keystone Jacks can also accommodate
cords and cables having various numbers of conductors.
The term keystone derives from the characteristic shape of the jack,
resembling the standard RJ-11 wall jack used to connect telephone sets, fax
machines, and dial-up computer modems to conventional telephone lines.
- Contacts are 50 microinches gold plating over 100 microinches nickel on
- 110 or Krone type IDC termination for 22-26 AWG solid wire.
- Color coded termination for easy identification and installation.
Available on both T568A and T568B wiring.
- 9 color choice of body provides great options for color designation of
- Dust caps/retention caps over termination provide strain relief.
- Supplied with color coded dust cover to stop foreign objects or dust.
1) What is the difference between Dual Link and Single Link?Which
do I need?
Dual link enables a higher resolution (1920 X 1080) and more channels. You
can view 2 displays simultaniously. If in doubt, order the Dual Link cable
because it is backwards compatible with Single Link.
2) I need a DVI-I to DVI-D cable -
What part number do I
A DVI-I enables digital and analog signals. A DVI-D only allows digital
signals. The part number to buy is DVIDL-length
3) Why are your DVI cables so much less?
You are coming right to the source. Our cables meet all wiring
specifications. We don't know why everybody else is so expensive.
4) Is there a distance limitation?
Yes. For digital DVI cables there is a 5 Meter distance limitation. If you go
longer the video results will be unpredictable and not guaranteed.
5) What is the TFT LCD?
TFT stands for "Thin Film Transistor" and describes the control elements that
actively control the individual pixels. For this reason, one speaks of so-called
"active matrix TFT's". LCD means "Liquid Crystal Display" and stands for
monitors that are based on liquid crystals.
6) What's the difference between CRTs size and TFT size?
The visible diagonal size of a CRT tub monitor is always smaller than the
tube's actual diagonal size. For example: a 17-inch CRT monitor has an edge area
and it's visible diagonal is only 16-inches. But TFT LCD monitors do not have an
edge area. This means that a 15-inch TFT LCD monitor is almost the same as the
17-inch CRT monitor.
7) What's the Contrast Ratio?
The Contrast Ratio is derived from the maximum and the minimum values for
8) What's the difference netween Digital and Analog Interface? Any
advantages or disadvantages?
TFT LCD monitors with an analog VGA interface dominate the market. Because it
is easy to install PC basis and not purchase a new graphics board. Although
digital TFT LCD monitors don't need to adjust clock and phase and the no signal
losses advantage. The Digital Interface standard has totally different
connectors and it is not easy to buy a suitable graphic board. So the analog TFT
LCD monitors still dominate the market. The following table gived you an
overview of the most important points:
No signal losses due to DA and AD conversion
Geometry, clock and phase settings unnecessary - therefore simple to use
Lower costs as less electronic circuitry required
Currently three standards (P & D (M1DA), DFP, and DVI)
Low availability of models with digital interfaces
Requires graphic board with digital output
Compatible with standard VGA boards on a broad installed PC basis
Not necessary to purchase seperate board
Clock and phase of the TFTs must be synchronized with the analog signal to
avoid pixel jitter, which is a relatively complex issue
Cables sensitive to external influences
High cost of signal conversion inside the display
Upgrade to digital interface not possible