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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What Is USB?
USB Short for Universal Serial Bus, an external bus standard that
supports data transfer rates of 12 Mbps.
Today just about every PC comes with Universal Serial Bus, or USB
ports. In fact, many computers will even have additional USB ports
located on the front of the tower, in additional to two standard USB ports
at the back. In the late 1990s, a few computer manufacturers started
including USB support in their new systems, but today USB has become
a standard connection port for many devices such as keyboards, mice,
joysticks and digital cameras to name but a few USB-enabled devices.
USB is able to support and is supported by a large range of products.
Adding to the appeal of USB is that it is supported at the operating
system level, and compared to alternative ports such as parallel or serial
ports, USB is very user-friendly. When USB first started appearing in the
marketplace, it was (and still is) referred to as a plug-and-play port
because of its ease of use. Consumers without a lot of technical or
hardware knowledge were able to easily connect USB devices to their
computer. You no longer needed to turn the computer off to install the
devices either. You simply plug them in and go. USB devices can also be
used across multiple platforms. USB works on Windows and Mac, plus
can be used with other operating systems, such as Linux, for example,
with a reliable degree of success.
Before USB, connecting devices to your system was often a hassle.
Modems and digital cameras were connected via the serial port which
was quite slow, as only 1 bit is transmitted at a time through a serial port.
While printers generally required a parallel printer port, which is able to
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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
receive more than one bit at a time — that is, it receives several bits in
parallel. Most systems provided two serial ports and a parallel printer
port. If you had several devices, unhooking one device and setting up the
software and drivers to use another device could often be problematic for
the user.
The introduction of USB ended many of the headaches associated with
needing to use serial ports and parallel printer ports. USB offered
consumers the option to connect up to 127 devices, either directly or
through the use of a USB hub. It was much faster since USB supports
data transfer rates of 12 Mbps for disk drives and other high-speed
throughput and 1.5Mbps for devices that need less bandwidth.
Additionally, consumers can literally plug almost any USB device into
their computer, and Windows will detect it and automatically set-up the
hardware settings for the device. Once that device has been installed you
can remove it from your system and the next time you plug it in,
Windows will automatically detect it.
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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Types of USB
USB 1x
First released in 1996, the original USB 1.0 standard offered data rates of
1.5 Mbps. The USB 1.1 standard followed with two data rates: 12 Mbps
for devices such as disk drives that need high-speed throughput and 1.5
Mbps for devices such as joysticks that need much less bandwidth.
USB 2x
In 2002 a newer specification USB 2.0, also called Hi-Speed USB 2.0,
was introduced. It increased the data transfer rate for PC to USB device to
480 Mbps, which is 40 times faster than the USB 1.1 specification. With
the increased bandwidth, high throughput peripherals such as digital
cameras, CD burners and video equipment could now be connected with
USB. It also allowed for multiple high-speed devices to run
simultaneously. Another important feature of USB 2.0 is that it supports
Windows XP through Windows update.
Short for USB On-The-Go, an extension of the USB 2.0 specification for
connecting peripheral devices to each other. USB OTG products can
communicate with each other without the need to be connected to a PC.
USB OTG addresses the need for devices to communicate directly for
mobile connectivity. USB OTG allows consumers to connect mobile
devices without a PC. For example, USB OTG lets consumers plug their
digital camera directly into a compliant printer and print directly from the
camera, removing the need to go through the computer. Similarly, a PDA
keyboard with a USB OTG interface can communicate with any brand
PDA that has a USB OTG interface.
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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
USB-OTG also provides limited host capability to communicate with
selected other USB peripherals, a small USB connector to fit the mobile
form factor and low power features to preserve battery life. USB OTG is
a supplement to the USB 2.0 specification.
Types of USB Connectors
Currently, there are four types of USB connectors: Type A, Type B, mini-
A and mini-B and are supported by the different USB specifications
(USB 1, USB 2 and USB-OTG).
USB A (Host)
Often referred to as the downstream connector, the Type A USB
connector is rectangular in shape and is the one you use to plug into the
CPU or USB hub.
USB B (Device)
Also called the upstream connector, the Type B USB connector is more
box-shaped and is the end that attaches directly to the device (such as a
printer or digital camera).
USB 1.1 specifies the Type A and Type B.
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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The USB 2.0 connector was too large for many of the new handheld
devices, such as PDAs and cell phones. The mini-B was introduced to
enable consumers to take advantage of USB PC connectivity for these
smaller devices.
USB 2.0 specifies the Type A, Type B and mini-B.
With the need to connect mobile devices without the aid of a computer,
the mini-A port was designed to connect the new generation of smaller
mobile devices.
USB OTG specifies the mini-A.
Certified Wireless USB
With an estimated 2 billion plus USB connected devices in the world and
a growing interest in wireless computing, it's no surprise that
development has turned to wireless USB. The USB Implementers Forum
has introduced Certified Wireless USB the newest extension to the USB
technology. Wireless USB applies wireless technology to existing USB
standards to enable wireless consumers to still use USB devices without
the mess of wires and worry of cords. Still in its infancy, the Wireless
USB specifications were made available to the public only in May 2005.
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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Notice . . . !!!
USB is capable of so much more than data transfer. Join us as we look at
some of the new gadgets that are taking advantage of this fact
Most of us have a printer, digital camera or MP3 player that we connect
to our computers using one of the little USB sockets situated at the front
and back of the machine.
You don't have to stop there, though. Those shiny USB cables can carry
any kind of data, including radio or television signals. They can also carry
a small electrical charge - enough to power a variety of gadgets that
might normally require batteries or their own power supply.
This opens up all sorts of interesting possibilities for new products - and,
needless to say, the computer industry has leapt at the opportunity to
design a motley assortment of weird and wonderful USB widgets for you
to spend your money on.
After printers, the most common USB devices are probably storage
devices of various types. These flash memory devices are light and
compact, but they tend to have limited capacity. If you need extra storage
for your ever-increasing collection of digital music or video clips, then
you might instead want to look at some of the USB hard disks that are
External USB-connecting hard disks are not unusual but many are big
and bulky and require their own power supply. That means more cables
and an ugly great power supply unit cluttering up your office. It also
means the drives aren't very portable.
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What is USB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Did You Know...
*Vangie 'Aurora' Beal
Writer, www.Webopedia.com Last updated: August 12, 2005
USB Info:
Frequently Asked Questions http://www.usb.org/about/faq/ans5
Commonly asked questions about USB Cables, Connectors, and
Networking with USB.
USB Implementers Forum http://www.usb.org/
USB Implementers Forum, Inc. is a non-profit corporation founded by the
group of companies that developed the Universal Serial Bus specification.
The USB-IF was formed to provide a support organization and forum for
the advancement and adoption of Universal Serial Bus technology.
Unusual uses for USB - Personal Computer World
USB is capable of so much more than data transfer. This article takes a
look at some of
the new gadgets that are taking advantage of this fact.
USB 2.0 - Hi-Speed USB - FAQ
This USB 2.0 FAQ is your first stop for general USB information and
those questions that seem to be on most people's minds. You are also
welcome to contribute your own answers to this wealth of information.
USB was introduced in 1997 but the technology didn't catch on until
the introduction of the Apple iMac in 1998 —ironic because USB was
developed by several PC-focused companies, including Compaq, DEC,
IBM, Intel and Microsoft ?!!!
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USB (یو اس بی) چیست؟
USB خلاصه گذرگاه سرى جهانى (Universal Serial Bus) می باشد، یک گذرگاه خروجی که انتقال اطلاعات را با سرعت 12مگابایت بر ثانیه پشتیبانی می کند.
امروز تقريباً هر كامپيوتر شخصى با گذرگاه سرى جهانى يا پورت‌هاى يو اس بى ارائه می شود. در واقع، حتى در خيلى از كامپيوترها پورت‌هاى يو اس بى اضافى در جلوی کیس و دو USB استاندارد اضافی در پشت کیس تعبیه شده است. در اواخر 1990، چند توليدكننده كامپيوترى پشتيبانى از يو اس بى را در سيستم‌هاى جديدشان شروع کردند اما امروزه يو اس بى يك پورت ارتباط استاندارد براى خيلى وسایل از قبيل صفحه‌هاى كليد شده است، موسها، دسته‌هاى بازى و دوربين‌هاى عكاسى ديجيتالى معروف  فقط  تعدادی از وسائل هستند که با يو اس بى فعال می شوند. يو اس بى قادر است هم پشتيبانى بكند و هم به وسيله يك دامنه بزرگ محصولات پشتيبانى شده است..
چیزی که به جاذبه USB افزوده است پشتیبانی در سطح سیستم عامل است و در مقایسه با انتخاب پورتهای موازی و یا سری، پورتهای USB خیلی کاربر پسند تر هستند.
پورتهای USB زمانیکه اولین بار وارد بازار شدند بخاطر ویژگی نصب کن و استفاده کن      (plug and play) مورد توجه قرار گرفتند زیرا استفاده از آن آسان بود.
 استفاده کنندگان بدون داشتن اطلاعات فنی زیادی یا آشنایی با دانش سخت افزار قادر بودند که وسایل USB را به کامپیوترشان وصل کنند. همچنین پیش از این لازم بود برای نصب وسایل، کامپیوتر را خاموش بکنید. شما به سادگی آنها را نصب کنید و بروید (از آن استفاده کنید).
وسایل USB می توانند در در چندین پایگاه بکار بروند. USB روی ویندوز و مکینتاش (Mac) کار می کند، به علاوه قادر است با سیستم عاملهای دیگر نیز از قبیل لینوکس (Linux) با قابلیت اطمینان بالایی کار کند.
پیش از USB، وصل نمودن وسایل به سیستمتان اغلب مشکل بود. مودمها و دوربینهای دیجیتالی که از طریق پورتهای سریال وصل می شدند کاملا کند بودند.
 بطور مثال فقط یک بیت هر دفعه با پورت سریال فرستاده می شد. در حالیکه پرینترها عموما به یک پورت موازی احتیاج دارند؛ کدامیک قادر است بیش از یک بیت در هر زمان دریافت کند. آن (پورت موازی) می تواند چندین بیت را دریافت کند. بسياری از سيستم‌ها دو پورت سرى فراهم كردند و يك پورت موازی.
اگر شما چندین وسیله داشتید، می بایست آن وسیله را باز کرده و نرم افزار و درایورها را برای استفاده وسیله دیگر نصب می کردید که این کار اغلب برای کاربر می توانست مشکل ایجاد کند.
در ابتدا USB به خیلی از گرفتاریهای استفاده از پورتهای سریال و موازی پرینتری پایان داد.
USB قدرت وصل نمودن 127 وسیله را بطور مستقیم یا با استفاده از یک هاب USB  به استفاده کنندگان می دهد. این (هاب USB) خیلی سریعتر از زمانیکه است که USB با نرخ 12مگابایت در ثانیه برای درایوهای دیسکی و خروجی های پرسرعت عمل انتقال داده را انجام می دهد و با 5/1مگابایت در ثانیه برای آنهایی که پهنای باند کمتری دارند.
به علاوه، استفاده کنندگان می توانند تقریبا هر وسیله USB را مستقیما به کامپیوترشان وصل کنند و ویندوز آنها را شناسایی کرده و بصورت خودکار سخت افزار را برای وسیله نصب می کند. زمانیکه آن وسیله نصب شد، شما می توانید آنرا از سیستمتان جدا کنید و زمان دیگری آنرا دوباره نصب کنید که ویندوز بصورت خودکار آنرا خواهد شناخت.
انواع USB:
USB 1x
در ابتداي انتشاردرسال 1996، براي سرعت داده 5/1 مگابيت در ثانيه توسط يو اس بى اوليه، استاندارد 0/1 پيشنهادگرديد. يو اس بى با استاندارد 1/1 از دو سرعت داده پیروی می کرد: 12 مگابيت در ثانيه براى وسائلی از قبيل درايوهاى ديسكى كه كارآيى خيلى سريع احتياج دارند و 5/1 مگابيت در ثانيه براى وسائل از قبيل دسته‌هاى بازى كه به پهناى باند خيلى كمتری احتياج دارند..

USB 2x
در سال 2002 يو اس بى 0/2 با مشخصه جديدتر- همچنين يو اس بى 0/2 سرعت بالا نيز ناميده مي شود-  معرفى گرديد. سرعت انتقال داده‌ها به وسيله يو اس بى براى كامپيوتر شخصى به 480 مگابيت در ثانيه افزايش داد، كه 40 بار تندتر از يو اس بى با مشخصه 1/1  است.
با زياد شدن پهناي باند، تجهيزات جانبي كامپيوتر از قبيل دوربينهاي ديجيتالي، رايترهاي سي دي و تجهيزات ويديويي كه رانده مان بالايي دارند را حالا مي توان با يو اس بي متصل نمود. آن همچنين اجازه مي دهد كه چندين وسيله سريع با هم اجرا شوند. ويژگى مهم ديگر يو اس بى 0/2  اين است كه از ويندوز XP هنگاميكه  ويندوز در حال به روز شدن است پشتيبانى ميكند.

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