USB (Universal Serial Bus)
Short History of USB
The USB was co-invented and established by Ajay Bhatt, a computer architect who had been working for Intel.
In 1994 seven companies that included Intel, Compaq, Microsoft, IBM, Digital Equipment Corporation (DEC), Nortel and NEC Corporation started the development of the USB. Their objective was to make it easier to connect peripheral devices to a PC and eliminate the mass amount of connectors. Factors involved included: creating larger bandwidths, streamlining software configurations and solving utilization problems for current interfaces.
USB was developed as an alternative to serial and parallel data transfer protocols. USB 1.0 was introduced in January 1996, USB 2.0 in 2000 and USB 3.0 in 2008.
USB 3.0, the latest version of USB , provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate.
Benefits of USB 3.0 over USB 2.0
- Transfer rates – USB 2.0 offers transfer rates of 480 Mbps and USB 3.0 offers transfer rates of 4.8 Gbps – that’s 10 times faster.
- Power consumption – USB 2.0 provides up to 500 mA whereas USB 3.0 provides up to 900 mA. The USB 3 devices will provide more power when needed and conserve power when the device is connected but idling.
- Addition of another physical bus – The amount of wires has been doubled, from 4 to 8. Additional wires require more space in both the cables and connectors, so there are new types of connectors.
- Dual Bus Architecture means More bandwidth – Instead of one-way communication, USB 3.0 uses two unidirectional data paths, one to receive data and the other to transmit while USB 2.0 can only handle only one direction of data at any time.
- Improved bus utilization – a new feature has been added using packets NRDY(Not Ready) and ERDY(Endpoint Ready) to let a device asynchronously notify the host of its readiness.
How to distinguish between a USB 2.0 USB 3.0 port?
USB 3.0 is very new and has limited presence as of today among the much more ubiquitous USB 2.0 devices. Some kind of identification was required to distinguish between both of them. What is that?
1. The Blue color of the USB port
2. Symbol ‘SS’ on the device/port (SS stands for Super Speed)