What is USB ?


USB, or Universal Serial Bus is a connectivity specification developed by computer and telecommunication industry members for attaching peripherals to computers.

 

Universal --- all peripherals share the same connector.

Serial      --- simply defines devices can daisy chain together.

 

Advantages:

It is designed to free all the troubles when installing external peripherals. It eliminates the hassle to open computer case for installing cards needed for certain devices.

It is designed to meet Microsoft Plug and Play (PnP) specification, meaning users can install, and hot-swap devices without long installation procedures and reboots.

It allows 127 devices to run at the same time on the bus.

USB bus provides two types of data transfer speed -- 1.5Mbps and 12Mbps and it can provide a maximum of 500mA of current to devices attached on the bus. All these features will only need one interrupt to operate on a computer equipped with USB ports.

 

History

Universal Serial Bus 1.1, the de facto external connectivity standard for Mac and PC, has picked up the speed after its slow adoption by peripheral manufacturers, users and PC OEMs. At present, numerous USB devices are out on the market because of  the speed of USB 2.0.

What is USB 2?
Drafted by Compaq, Hewlett Packard, Intel, Lucent, Microsoft, NEC and Philips, USB Specification version 2.0 will increase device data throughout up to 480Mbps, 40 times faster than USB 1.1 devices. Originally, the new USB 2 was only intended to go as fast as 240Mbps but with the team engineering effort, the speed was raised to 480Mbps.

With the increased speed, computer consumers will benefit with an additional range of high performance peripherals. Even with multiple high-speed peripherals connected to a USB 2 bus, they will not have to worry about hitting the bandwidth bottleneck. The new specification also inherits the current USB Plug and Play and hot-swapping capability as well as providing backward compatibility for USB 1.1 hardware.