[Theory] Universal Serial Bus (USB)

[ErmaC]

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http://www.activemp.com/assets/superspeed-...30_overview.pdf

 

 

Universal Serial Bus

 

USB is an external bus allowing you to connect external peripherals to your PC such as mice, keyboards, digital cameras, external hard disk drives, external CD recorders, printers, scanners, etc. There are two versions available: 1.1 and 2.0. USB 1.1 has a maximum transfer rate of 12 Mbps (around 1.5 MB/s), while USB 2.0 has a maximum transfer rate of 480 Mbps (around 60 MB/s). Since around 1998 all PCs come with USB ports on the motherboard. To each USB port it is possible to connect up to 127 peripherals.

 

The most common USB plugs are “Type A”, used on the USB ports located on the PC, and “Type B”, located on peripherals such as printers and scanners. Smaller devices, like digital cameras, use smaller plugs, usually proprietary (i.e. without any standardization and with a layout and pinout that depends on the peripheral make and model).

 

http://www.hardwaresecrets.com/fullimage.php?image=2918

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Figure 1: USB ports on a motherboard.

 

http://www.hardwaresecrets.com/fullimage.php?image=2919

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Figure 2: Standard USB plugs.

 

 

 

Everything You Need to Know About USB and USB 3.0

 

 

 

Without the Universal Serial Bus standard we’d live in a world that Apple, with its infinite variations of specialized port formats and cable changes, would love to make possible. Think of the margins! But even the design-centric Apple has succumbed to the lure of USB, that ubiquitous little port that connects our gadgets to our computers. Proprietary on one end and universal on the other, USB has the highest consumer success rate — getting shipped on over 3 billion devices in 2008 — according to research firm In-Stat. And now there’s an upgrade to USB on the way. Here’s what you need to know about the coming USB 3.0.

 

It’s fast: Dubbed Super-Speed USB, it will offer transfer speeds of 4.8 Gbps compared with High-Speed USB 480Mbps transfer speeds.

It’s backwards compatible: Your existing USB 2.0 stuff will also work on the 3.0 ports and vice versa, although you won’t get the “super speeds.”

It’s coming soon: Vendors will ship some boards at the end of this year, so mainstream consumers should see them on their computers and certain devices starting in 2010.

It’s powerful: Like USB 2.0, it will transmit electricity, which means you can still use it to charge your gadgets.

It’s energy efficient: It supports reduced power operation and an idle power mode, but it will still make your CPU work like crazy to help it reach those fast data transfer speeds.

It’s backed by all vendors: Early on, both AMD and Nvidia were kind of miffed at Intel for holding back on some of the specification details, but that’s all over, and everyone’s now on board.

It will end the longing for FireWire’s resurrection: The faster speeds will mean that sending data to an external hard drive isn’t as grindingly slow.

Or will it instead keep the FireWire flame lit? Without the threat of FireWire competing against USB products, it’s possible we won’t see prices for technology drop as rapidly as they did with previous generations.

Devices that generate big data will be the first to appear with the standard. Large flash drives, hard drives, video cameras and high-end cameras will be the first to have the technology because they can benefit from faster data transfer rates.

It’s a way to create the anti-cloud: Instead of accessing everything online either through downloads or streaming, you can store gobs of content on hard drives, and have relatively fast access to it with USB cables. That might be handy if strict data caps are implemented or you think you’ll be without broadband for a while.