What is NEMA? -
NEMA Enclosure Types
 The National
Electrical Manufacturers Association or NEMA
for short has established a range of standards for electrical
equipment enclosures. For more detailed
and complete information, NEMA Standards Publication 250. You can
reach the National Electrical Manufacturers Association at: http://www.nema.org/
Here is a
partial list of the NEMA standards that some of Stealth's products
adhere to:
NEMA 4
- Type 4 enclosures are intended for indoor or outdoor use primarily
to provide a degree of protection against windblown dust and rain,
splashing water, and hose-directed water; and to be undamaged
by the formation of ice on the enclosure. They are not intended
to provide protection against conditions such as internal condensation
or internal icing.
NEMA 4X
- Type 4X enclosures are intended for indoor or outdoor use primarily
to provide a degree of protection against corrosion, windblown
dust and rain, splashing water, and hose-directed water; and to
be undamaged by the formation of ice on the enclosure. they are
not intended to provide protection against conditions such as
internal condensation or internal icing.
NEMA 12
- Type 12 enclosures are intended for indoor use primarily to
provide a degree of protection against circulating dust, falling
dirt, and dripping noncorrosive liquids. They are not intended
to provide protection against such conditions as internal condensation.
NEMA
13 -Type 13 enclosures are intended for indoor use primarily
to provide a degree of protection against lint, dust, spraying
of water, oil and noncorrosive coolant. They are not intended
to provide protection against conditions such as internal condensation.
Stealth Computer
Corporation has embraced these NEMA industry standards to ensure
higher quality products offering benchmark comparisons for our
customers.
COMPARISON
BETWEEN NEMA ENCLOSURE TYPE NUMBERS AND IEC ENCLOSURE CLASSIFICATION
DESIGNATIONS
NEMA
Enclosure
Type Number |
IEC
Enclosure
Type Number |
| NEMA
4 & 4X |
IP56 |
| NEMA
12 |
IP52 |
| NEMA
13 |
IP54 |
NOTE: This comparison
is based on tests specified in IEC Publication 529
TABLE A-1 CONVERSION OF NEMA TYPE NUMBERS TO IEC CLASSIFICATION
DESIGNATIONS (CANNOT BE USED TO CONVERT IEC CLASSIFICATION DESIGNATIONS
TO NEMA TYPE NUMBERS)
What is Smart Fan Adaptive Cooling?
Some models of Stealth's Industrial Grade PCs employ the "Smart Fan Adaptive
Cooling Feature" which is a Temperature/Speed controlled air fan option.
Operating fans at full speed continuously can be disastrous to a computer
operating in an industrial environment. The dust, not necessarily the
temperature can be of most concern. Some installations have toxic particles in
the air such as sulfur, which combines with the delicate copper traces on the
computer cards. In time, those copper traces will pulverize causing a failure or
even worse, a highly intermittent and difficult to diagnose fault. Even
non-toxic dust, over time will create a film on the computer chips, virtually
insulating the components from the benefits of airflow.
Another consideration is the overall reliability of the components, which
demands keeping thousands of the transistor junctions in the integrated chips at
a fairly constant temperature. The speed of most DC fans is approximately
proportional to the applied voltage. Smart Fan controller uses this principle,
applying a smooth DC voltage, which varies from 55 to nearly 100% of the 12 VDC,
supplied to the controller. Minimum voltage is limited to 55% so that the fan
operates down to one-half of its nominal rated voltage. Smart Fan controller
senses temperature downstream from the computer chips and holds it nearly
constant. A sensor connected to the controller continuously monitors
temperature. The controller powers high output air fans, automatically adjusting
their speed over the operating range from fan idle temperature at 23 degrees C
to a full speed reached at 35 degrees C. At 45 degrees C an audible alarm will
sound to alert the operator about the potential problem.
Additional benefits of the Smart Fan controller is the buffering of the 12 VDC
power supply from pulsation caused by DC fans. As well the fan noise is reduced
considerably when running in a normal operating ambient temperature, as the fans
no longer have to work as hard.
What is Intrinsically Safe?
Intrinsic safety is a protection concept deployed in sensitive and
potentially explosive atmospheres. Intrinsic safety relies on the
equipment being designed so that it is unable to release
sufficient energy, by either thermal or electrical means, to cause
an ignition of a flammable gas.
Intrinsically safe is achieved by limiting the amount of power
available to the electrical equipment in the hazardous area to a
level below that which will ignite the gases.
In order to have a fire or explosion, fuel, oxygen and a source of
ignition must be present. An intrinsically safe system assumes the
fuel and oxygen is present in the atmosphere, but the system is
designed so the electrical energy or thermal energy of a
particular instrument loop can never be great enough to cause
ignition.
Traditionally, protection from explosion in hazardous environments
has been accomplished by either using explosion proof equipment
which can contain an explosion inside an enclosure, or
pressurization and/or purging which isolates the explosive gas
from the electrical equipment.
Intrinsically safe equipment cannot replace these methods in all
applications, but where possible can provide significant cost
savings in installation and maintenance of the equipment in a
Hazardous area. The basic design of an intrinsic safety barrier
uses Zener Diodes to limit voltage, resistors to limit current and
a fuse.
Most applications require a signal to be sent out of or into the
hazardous area. The equipment mounted in the hazardous area must
first be approved for use in an intrinsically safe system. The
barriers designed to protect the system must be mounted outside of
the hazardous area in an area designated as Non-hazardous or Safe
in which the hazard is not and will not be present.
APPROVALS
Intrinsic safety equipment must have been tested and approved by
an independent agency to assure its safety. The customer should
specify the type of approval required for their particular
application. The most common Agencies involved are as follows:
COUNTRY AGENCY
USA - FM, UL
Canada - CSA
Great Britain - BASEEFA
France - LCIE
Germany - PTB
Italy - CESI
Belgium - INEX
USB VS FireWire
 The ever-present Universal Serial Bus (USB) is now a standard
feature on virtually every new PC. The "jack-of-all-trades"
nature of USB has made it ideal for connecting additional
peripherals without opening the computer. The drawback of the
original USB standard (v1.1) was its relatively slow speed
however most new PCs have adopted version 2.0 offering
theoretical speeds up to 480Mbs. Both USB and Firewire feature
"hot-swapping", which means you won't need to shut down and
reboot your PC to attach or remove a peripheral.
FireWire, (technically known as IEEE 1394) is a serial
input/output technology invented by Apple Computer with data
transfer rates up to 400 megabits per second. A FireWire upgrade
has been released and IEEE 1394b will offer transfer rates of up
to 800 Mbps, reportedly fast enough to copy an entire CD in
seconds. Firewire 800 is starting to show up in the market now
with mass-market adoption expected in 2004.
While the two serial buses seem similar, they are intended to
fulfill different bandwidth and cost needs. 1394 can move more
data in a given amount of time, but is considerably more
expensive than USB due to its more complex protocol and
signaling rate. Applications that are best suited for 1394 are
disk drives, high quality video streams and other high bandwidth
applications. USB is appropriate for middle and low bandwidth
applications such as audio, scanners, printers, keyboards, and
mice.
USB and 1394 are complementary technologies. 1394 is for devices
where high performance is a priority and price is not, while USB
is for devices where price is a priority and high performance is
not.
| |
Firewire
IEEE 1394 , 1394b |
USB
Vers. 1.0/1.1/2.0 |
Data transfer rate
(MB/s) |
400Mbs, 800Mbs |
1.2,
12, 480Mbps |
Maximum number of
connected devices |
63 |
127 |
|
Hot-swap? |
Yes |
Yes |
|
Plug-and-Play? |
Yes |
Yes |
Cable length between
devices |
4.5
/100 meters |
5
meters |
Embedded
power line |
Yes |
Yes |
|
Peripheral devices |
D-Camcorders
D-Cameras
Set-Top Boxes
HDTV
DVD-ROM, RAM
Hard Disk drives
Printers
Scanners |
Keyboards
Mice
PC Monitors
Joysticks
DVD-ROM, RAM
Low-resolution D-Cameras
Low-speed CD-ROM, RW
Modems
Printers
Scanners |
|
Relative cost
|
Higher |
Lower |
For more information
about USB or
Firewire:
What is Wi-Fi or 802.11?
 Wi-Fi
is short for Wireless Fidelity, Wi-Fi is a user-friendly name for devices
that have been certified by (WECA)
Wireless Ethernet
Compatibility Alliance to conform to the industry-standard wireless
networking specification IEEE 802.11b. Wi-Fi began appearing in products
in the late part of 1998 and today they are visible everywhere. The
current standard provides access to Ethernet networks such as a corporate
LAN or the Internet at super-fast speeds of up to 11 megabits per second
in the 2.4GHz band. (for example, 2.4GHz for 802.11b or 11g, 5GHz for
802.11a)
Wi-Fi connections can be made up to about 300 feet away from a "hot spot"
(slang for a Wi-Fi networking node). When your notebook or PDA has a Wi-Fi
networking card or built-in chip, you can surf the Internet at broadband
speeds wirelessly. Wi-Fi networking nodes are proliferating globally; many
Starbucks locations, for instance, offer access to Wi-Fi hot spots for a
fee. Many portable PCs today have IEEE 802.11b built-in; those that don't
can be adapted via Wi-Fi connectivity PC Cards. Wi-Fi is also the basis
for some home networking products, allowing you to share high-speed
Internet connections without the hassle of running cables. Late last year,
products featuring a newer wireless networking specification, IEEE 802.11a
(called Wi-Fi5 by WECA), debuted. This standard provides transmission
speeds of up to 54 mbps. Wireless networking is expected to grow in
popularity as a practical, flexible way to replace some LANs. For a chart
on Wireless LAN standards
click here.
Stealth has recently introduced some of their LittlePC series computers
with PCMCIA or PC Card adapters built right in. This exciting option
allows a small footprint PC to be deployed into a Wi-Fi application with
relative ease. Please have a look at the
new
LittlePCs with this amazing capability
here.
What is Gigabit Ethernet?
Breakneck speed on the Ethernet highway
In short, Gigabit Ethernet
is the same Ethernet that we already know and use, but 10 times faster
than Fast Ethernet and 100 times faster than Ethernet. It also supports
additional features that accommodate today's bandwidth-hungry
applications and match the increasing power of the desktop and server.
Gigabit Ethernet is a transmission technology based on the Ethernet
frame format and protocol used in local area networks (LANs) and
provides a data rate of 1 billion bits per second (one gigabit). Gigabit
Ethernet is defined in the
IEEE 802.3
standard and is currently being used as the standard backbone in many of
today's enterprise networks.
Gigabit Ethernet
compatibility with Ethernet preserves investments in network
administrator expertise and support staff training, while taking
advantage of user familiarity. Just as 100 Mbps Fast Ethernet provided a
low-cost, incremental migration path from 10 Mbps Ethernet, Gigabit
Ethernet is providing the next logical migration to 1000 Mbps bandwidth.
A newer standard, 10-Gigabit Ethernet is also becoming available.
Since its introduction in the early 1980s, Ethernet deployment has
quickly overshadowed networking connection choices such as Token Ring
and ATM.
SCSI - The Ins and Outs - A brief overview
What it
means and the types available
What does the term "SCSI" mean?
The term "SCSI" (pronounced "scuzzy") Small Computer System Interface,
the technology interface is mostly used to connect mass-storage devices
such as hard disk drives, tape devices and CD-drives but is also often
used to connect scanners and other optical devices. SCSI devices can be
internal or external.
 So what exactly is SCSI?
SCSI is is a high-speed, intelligent peripheral I/O bus with a device
independent protocol. It is an entirely different interface than the
more popular IDE. It is more of a system level interface, meaning that
it does not only deal with disk drives. It is not a controller, like
IDE, but a separate bus that is hooked to the system bus via a host
adapter. A single SCSI bus can hold up to eight units, each with a
different SCSI ID, ranging from 0 to 7. The host adapter takes up one
ID, leaving 7 ID's for other hardware. SCSI hardware typically consists
of hard drives, tape drives, CD-ROMs and scanners. Many high-end systems
have built-in SCSI support. There is usually an adapter card or an
adapter built in to the motherboard.
The advantages are that it is fast, reliable, it allows you to connect
multiple devices in a chain and it is easily expandable.
What are the SCSI Types?
There are really only three basic specifications of SCSI:
SCSI-1 was standardized by ANSI in 1986. The initial implementation
of SCSI (now called SCSI-1) was designed primarily for Narrow (8-bit),
single-ended, synchronous or asynchronous disk drives and was very
limited relative to today's SCSI. It includes synchronous and
asynchronous data transfers at speeds up to 5 Mbytes/sec. The standard
connectors are the familiar 50-pin, female, low-density non-shielded
connector for internal wiring and the equally familiar 50-pin, male,
shielded "centronics" type connector for external wiring
SCSI-2: An update that became an official standard in 1994, a key
component of SCSI-2 was the inclusion of the Common Command Set (CCS) --
the 18 commands considered an absolute necessity for support of any SCSI
device. You also had the option to double the clock speed from 5 MHz to
10 MHz (Fast SCSI), double the bus width from 8 bits to 16 bits and
increase the number of devices to 15 (Wide SCSI), or do both (Fast/Wide
SCSI). Finally, SCSI-2 added command queuing, which means that an SCSI-2
device can store a series of commands from the host computer and
determine which ones should be given priority.
 SCSI-3: Quickly on the heels of SCSI-2 came SCSI-3, debuting in
1995. The interesting thing about SCSI-3 is that a series of smaller
standards have been built within its overall scope. Because of this
continually evolving series, SCSI-3 is not considered to be a completely
approved standard. Instead, some of the specifications developed within
it have been officially adopted. These standards are based on variations
of the SCSI Parallel Interface (SPI), which is the way that SCSI devices
communicate with each other. Most SCSI-3 specifications begin with the
term "Ultra" (Ultra for SPI variations, Ultra2 for SPI-2 variations and
Ultra3 for SPI-3 variations). The Fast and Wide designations work just
like their SCSI-2 counterparts, with the Fast designation meaning that
the clock speed is double that of the base version, and the Wide
designation meaning that the bus width is double that of the base.
|
Type |
Speed |
Hard drive / peripheral connections |
Ultra320 SCSI
(16-bit Wide) |
320 MByte/sec |
State-of-the-art hard
drives |
Ultra160 SCSI
(16-bit Wide) |
160 MByte/sec |
Hard drives |
Ultra2 SCSI
(16-bit Wide) |
80 MByte/sec |
Hard drives |
Ultra Wide SCSI
(16-bit Wide) |
40 MByte/sec |
Hard drives and tape
drives |
Ultra SCSI
(8-bit Narrow) |
20 MByte/sec |
CD-R, CD-RW, tape,
removable storage (Jaz), and DVD drives |
SCSI-2, Fast SCSI
(8-bit Narrow) |
10 MByte/sec |
Scanners, Zip drives,
and CD-ROM |
For more information
browse to the SCSI Trade Association at:
http://www.scsita.org
FAQ: What is Moores Law?
40 years and counting is it still relevant?
 One topic of discussion that regularly pops up among techies
predominantly in the computer industry is "Moores Law". Moore's
Law has been a valuable benchmark for the developments in
microelectronics and information processing technologies. It
essentially relates to a statement made by Intel's co-founder
Gordon Moore back in 1965, where he proclaimed that the number
of transistors in a processor would double every year, later
revised to every two years.
The press called it "Moore's Law" and the name has stuck.
Moore's original assumption was included in a paper entitled
‘Cramming more components onto integrated circuits', published
in the April 19, 1965 edition of Electronics magazine. To view
the original paper,
click here. Moore observed an exponential
growth in the number of transistors per integrated circuit and
predicted that this trend would continue. Through Intel's
relentless technology advances, the doubling of transistors
every couple of years, has been maintained, and still holds true
today.
Traditionally, it has been kept alive by decreasing the size
taken up by a single transistor within a processor. And
according to Craig Barrett, Intel's, CEO that trend will
continue for a long time. In fact, Barrett said that based on
current research, the shrinking of transistors will continue
until we reach the point where transistors are down to the size
of 5 nanometers -- about the width of 50 hydrogen atoms. The
transistor remains the driving force behind new technologies.
"There is so much space in the transistor left and we are going
to push it." "You would be surprised to see where we end up."
Barrett said.
64 Bit Computing
The future is upon us in microprocessor technology
 AMD,
Intel, Microsoft, and Apple, all agree that 64-bit processors matter for
two reasons; memory and processing power. One of the crucial benefits of
64-bit chips is that they can manage more than 4GB of memory. Today's
32-bit processors work with 32 bits of data per clock cycle and can
address up to 4GB of memory. Its only in recent times top systems have
utilized more than 1GB of memory and many industry experts agree that it
will be some time before consumers would require more than 4GB. But
clearly it's going to happen eventually.
For example, Intel's Itanium 64-bit processor works with 64 bits of data
at a time and can address up to 16 terabytes of memory. The new processors
should dramatically increase processing speed for complex math and
graphics applications.
Why would anyone need it?
64-bit processing today may be overkill for most desktop users however it
will grow into a powerful and essential tool for many applications. Fast
processors become increasingly necessary to run specific tasks such as
complex database management systems, computer-aided design applications,
animation, technical and scientific applications. The move to 64 bits has
proven necessary for high-end workstations and servers. Intel, IBM, Sun
Microsystems all make 64-bit chips for workstations and servers, but those
chips require completely different hardware and software than that found
on consumer PCs.
 Of
course the processor isn't the only player here as operating system and
applications are required. Intel introduced the 32-bit 80386 processor in
1985, however Microsoft didn't ship a fully 32-bit operating system
(Windows XP) until 15 years later. It won't take nearly as long to move to
64-bit OS as Microsoft has developed a 64-bit version of desktop Windows (dubbed
Windows XP 64-Bit Edition for 64-Bit Extended Systems) in beta, as
well as a 64-bit version of Windows Server 2003. Note: 64-bit operating
systems are common in the Unix/Linux world with systems like Sun Solaris,
HP-UX and IBM AIX which have been running on 64-bit processors for years.
If all you do is run Microsoft Office and e-mail you probably aren't
bumping up against any of the limits of the current 32-bit processors.
Nevertheless if you're running scientific or graphics apps on a
workstation, or if you're an extreme gamer, the improved processing power
and graphics capabilities would most surely interest you.
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