1. USB release dates
USB (universal serial bus) was developed as an alternative to serial and parallel data transfer protocols. USB 1.0 was introduced in January 1996.
2. Changes in USB 3.0
USB 3.0 is one of the most anticipated changes to the PC in years. Here is a summary of the major changes:
- SuperSpeed — New higher signaling rate of 5Gbps (625MB/sec)
- Dual-bus architecture — Low-Speed, Full-Speed, and High-Speed bus plus SuperSpeed bus
- Asynchronous instead of polled traffic flow
- Dual-simplex simultaneous bi-directional data flow for SuperSpeed instead of half-duplex unidirectional data
- Support for streaming
- Fast Sync –N-Go technology
- Support for higher power
- Better power management
3. The Low-Speed, Full-Speed, High-Speed and SuperSpeed confusion
4. Actual data throughput
Actual data throughput is usually much less than the maximum advertised USB specification and is a function of many variables, including overhead. Actual throughput in practice is typically up to 35 - 40MB/sec for USB 2.0 and may exceed 400MB/sec for USB 3.0. NEC recently demonstrated its new USB 3.0 controller transferring 500MB in 4.4 seconds or “only” 113.6MB/sec. Symwave and MCCI claim to have demonstrated over 270MB/sec data throughput at the Intel Developer Forum in September 2009.
6. Power
One of the most significant innovations in USB over serial and parallel protocols is the addition of power to the specification. Plug in a USB device and it can be powered from the host computer.
7. Limitations
We’ve already discussed some of the USB limitations:
- Maximum data rates
- Actual data throughput
- Cable length and total length
- Power
0 comments:
Post a Comment