USB 1.0, USB 2.0, USB 3.0 : Guide

By soumitra, Gaea News Network
Tuesday, September 8, 2009

usbkeyUSB or Universal Serial Bus is a standard connection method to connect different computer peripherals to the computer with an intention to replace many varieties of serial and parallel ports to connect different devices. Today you can connect a mouse, keyboard, gamepad, digital camera, mobile phone, printer, PMP, flash drives, external hard drives to name a few. After its introduction in 1996 when there were several multitude of connectors at the back of the PCs to connect various devices, the USB has been welcomed by a group of Core Companies like, IBM, Intel, Microsoft, Compaq, Digital, Northern Telecom. Later the USB is standardized by the USB Implementers Forum. Let us take a deeper look at the technology.

Key Features

  • Up to 127 devices can connect to the host, either directly or by way of USB hubs.
  • A USB cable has two wires for power (+5 volts and ground) and a twisted pair of wires to carry the data.
  • On the power wires, the computer can supply up to 500 milliamps of power at 5 volts.


What is USB 1.0?

It is basically the first standard definition of USB it supports a low speed rate of 1.5 Mbit/s. It is intended primarily to save cost in low-bandwidth human interface devices (HID) such as keyboards, mice, and joysticks.

What is USB 1.1?

It is the next generation of the USB Devices. It supports full speed rate of 12 Mbit/s. It is very similar to the previous standard except each bit transfer is 8 times faster. All USB hubs support full speed.

What is USB 2.0?

A hi-speed (USB 2.0) rate of 480 Mbit/s was introduced in 2001. All hi-speed devices are capable of falling back to full-speed operation if necessary; they are backward compatible. Connectors are identical to the original USB.

What is USB 3.0?

It boasts a much more higher data transfer bandwidth of SuperSpeed (USB 3.0) rate at 5.0 Gbit/s. The USB 3.0 specification was released by Intel and partners in August 2008. New devices supporting USB 3.0 is expected to be produced by the end of this year. The new connectors will be backward compatible but they will include a new wiring system to allow for full duplex communication.

Different type of USB Connectors

There are several types of standard connectors available in the market.
Type A : This is the most common USB connector. Every PC is equipped with some USB A receptacles and we connect the devices like keyboard, mouse etc through this port.
Type B : This is a square shaped connector with beveled exterior corner on one side. Printers mostly use this connection type. This two connector type scheme prevents any possibility of creating any potentially dangerous electrical loop.

Mini USB : This is the most common port found on consumer digital cameras and many other mobile devices.
Micro USB : Similar to mini USB but is more slimmer and is designed to be more resistant to wear than the mini USB ports. This standard is currently being adopted by many mobile manufacturers and it is also being adopted as a port for charging the mobiles.



  • Low Cost : Cheapest connectors and simplest circuitry needed to handle.
  • Expandability : Add more than one devices to a single port.
  • Durable : The connectors are tough enough to undergo modest torture on them.
  • Auto Configuration : No Hassles.
  • Hot plugging : Plug in or remove connectors while computer is turned on.
  • Outstanding Performance : No Compromise on speeds.
  • Provides Power to Bus : No need to use AC Adapters for low power electronic gadgets.
  • Identical third party hardware platform
  • Only moderate force is required to make or break a connection


The USB Process

Basically there are three types of processes for three different type of data transfer needs.
Interrupt : Typical Human interface device like mouse or keyboard uses this type of connection. They need to send very little data over time, so they choose interrupt mode.
Bulk : Devices like printer needs to receive data in a big packet. So, they choose bulk transfer mode.
Isochronous : This is used for streaming devices like speaker systems. Data is transferred in real time to them.

Intially the host assigns an address to each of the devices when it powers up. The total bandwidth of the USB is divided between the USB devices that are attached to it. Firstly, the isochronous devices get their share of data to function properly and the rest of data packets/frames are divided between interrupt and bulk transfer mode devices. If 90% of total available bandwidth is used then no more isochronous devices are allowed.

Hope this discussion would be enough as a basic knowledge to use ‘em.


1. Wikipedia
2. HowStuffWorks

August 26, 2010: 5:04 am

I have to order a cable from ebay. Now I know what to buy, it’s much clear, thank you.

August 25, 2010: 3:10 am

Sell it and buy Nexus1, android

March 30, 2010: 10:39 am

I’m looking for usb cable for my nokia 2630 - it seems to be micro, but it is not flat like micro is… it’s more like usb B usually for printers but smaller than usb B mini…
What to do?

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