Dell Vostro 3888 Service Manual page 9

commonly known as USB 2.0 and 1.1 respectively, the slower modes still operate at 480 Mbps and 12 Mbps respectively and are kept to
maintain backward compatibility.
USB 3.0/USB 3.1 Gen 1 achieves the much higher performance by the technical changes below:
• An additional physical bus that is added in parallel with the existing USB 2.0 bus (refer to the picture below).
• USB 2.0 previously had four wires (power, ground, and a pair for differential data); USB 3.0/USB 3.1 Gen 1 adds four more for two
pairs of differential signals (receive and transmit) for a combined total of eight connections in the connectors and cabling.
• USB 3.0/USB 3.1 Gen 1 utilizes the bidirectional data interface, rather than USB 2.0's half-duplex arrangement. This gives a 10-fold
increase in theoretical bandwidth.
With today's ever increasing demands placed on data transfers with high-definition video content, terabyte storage devices, high
megapixel count digital cameras etc., USB 2.0 may not be fast enough. Furthermore, no USB 2.0 connection could ever come close to the
480Mbps theoretical maximum throughput, making data transfer at around 320 Mbps (40 MB/s) — the actual real-world maximum.
Similarly, USB 3.0/USB 3.1 Gen 1 connections will never achieve 4.8Gbps. We will likely see a real-world maximum rate of 400MB/s with
overheads. At this speed, USB 3.0/USB 3.1 Gen 1 is a 10x improvement over USB 2.0.
Applications
USB 3.0/USB 3.1 Gen 1 opens up the laneways and provides more headroom for devices to deliver a better overall experience. Where USB
video was barely tolerable previously (both from a maximum resolution, latency, and video compression perspective), it's easy to imagine
that with 5-10 times the bandwidth available, USB video solutions should work that much better. Single-link DVI requires almost 2Gbps
throughput. Where 480Mbps was limiting, 5Gbps is more than promising. With its promised 4.8Gbps speed, the standard will find its way
into some products that previously weren't USB territory, like external RAID storage systems.
Listed below are some of the available SuperSpeed USB 3.0/USB 3.1 Gen 1 products:
• External Desktop USB 3.0/USB 3.1 Gen 1 Hard Drives
• Portable USB 3.0/USB 3.1 Gen 1 Hard Drives
• USB 3.0/USB 3.1 Gen 1 Drive Docks & Adapters
• USB 3.0/USB 3.1 Gen 1 Flash Drives & Readers
• USB 3.0/USB 3.1 Gen 1 Solid-state Drives
• USB 3.0/USB 3.1 Gen 1 RAIDs
• Optical Media Drives
• Multimedia Devices
• Networking
• USB 3.0/USB 3.1 Gen 1 Adapter Cards & Hubs
Compatibility
The good news is that USB 3.0/USB 3.1 Gen 1 has been carefully planned from the start to peacefully co-exist with USB 2.0. First of all,
while USB 3.0/USB 3.1 Gen 1 specifies new physical connections and thus new cables to take advantage of the higher speed capability of
the new protocol, the connector itself remains the same rectangular shape with the four USB 2.0 contacts in the exact same location as
before. Five new connections to carry receive and transmitted data independently are present on USB 3.0/USB 3.1 Gen 1 cables and only
come into contact when connected to a proper SuperSpeed USB connection.
Technology and components 9