Connecting Two PCs Using a USB-USB Cable

Introduction


A very easy way to connect two PCs is using a USB-USB cable. Connecting two PCs with a cable like this you can transfer files from one PC to another, and even build a small network and share your Internet connection with a second PC. In this tutorial we will explain you how to connect two PCs using a cable like this.

The first thing you should be aware of is that there are several different kinds of USB-USB cables on the market. The one used to connect two PCs is called “bridged” (or “USB networking cable”), because it has a small electronic circuit in the middle allowing the two PCs to talk to each other. There are the so-called A/A USB cables that, in spite of having two standard USB connectors at each end, don’t have a bridge chip and cannot be used to connect two PCs. In fact, if you use an A/A USB cable you can burn the USB ports of your computers or even their power supplies. So, these A/A USB cables are completely useless. A/B USB cables are used to connect your computer to peripherals such as printers and scanners, so they also won’t fit your needs.


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Figure 1: USB-USB bridged cable.


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Figure 2: A close-up of the bridge located in the middle of the cable.

As for speed, the bridge chip can be USB 1.1 (12 Mbps) or USB 2.0 (480 Mbps). Of course we suggest you to buy a USB 2.0 bridged cable, because of its very high-speed. Just to remember, the standard Ethernet network works at 100 Mps, so the USB 2.0 cable will provide you a transfer rate almost five times higher than a standard network connection.

We decided to open the bridge located on the middle of our cable just to show you that this kind of cable really has a bridge chip, and that’s why it is more expensive than a simple A/A USB cable that doesn’t have any circuit at all.


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Figure 3: Bridge chip used in our cable.

Now that you know the kind of cable that you should buy (on the top of this page we are listing several places you can buy this cable online), let’s talk about its installation.

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USB 3.0

Everything You Need to Know About USB 3.0, Plus First Spliced Cable Photos

 

 

No doubt you’re familiar with the Universal Serial Bus – we ranked it as our top PC innovation of all time. But what do you know about the next version of this ubiquitous interface? USB 2.0 (otherwise known as USB Hi-Speed) boosted the original 12Mbps data rate to 480Mmb/s over eight years ago, and now USB 3.0 (dubbed USB Superspeed) is set to multiply that bandwidth tenfold. Intel released the Extensible Host Controller Interface to hardware partners last week after some reported disputes with AMD and Nvidia (who, afraid Intel would have a jump start in incorporating the tech in chipsets, threatened to develop their own USB standard). But how does this affect you? We dug up some new information about USB 3.0, got our hands on the new connectors, and even took a look inside the new cables.

(Edit made to clarify xHCI release)


USB 3.0 will be backwards-compatible with USB 2.0

Like the upgrade from USB 1.1 to 2.0, the new 3.0 connectors and cables will be physically and functionally compatible with hardware from the older specs. Of course, you won’t be able to maximize your bandwidth unless you’re using a USB 3.0 cable with Superspeed devices and ports, but at least plugging a 3.0 cable into a 2.0 port won’t blow up your PC. The spec’s compatibility lies in the design of the new connectors. USB 2.0 cables worked off of four lines – a pair for in/out data transfer, one line for power, and the last for grounding. USB 3.0 adds five new lines (the cable is noticeably thicker), but the new contacts sit parallel to the old ones on a different plane, as opposed to being adjacent to them. This means you’ll be able to differentiate between 2.0 and 3.0 cables just by looking at the ends.


At first glance, the USB 3.0 connector looks just like the 2.0 design

The maximum speed of USB 3.0 is 4.8Gbps

It’s true: USB 3.0 SuperSpeed will be 10 times faster than the 480Mbps limit of the 2.0 spec. The example Intel likes to give out when talking about the new speed is that transferring a 27GB HD movie to your future media player will only take 70 seconds with USB 3.0, while it would take 15 minutes or more with 2.0. Keep in mind that you’re only going to be able to take advantage of this speed if your portable storage device can write data that quickly. Solid state devices will benefit most from the speed boost, while magnetic hard disks will be limited by their RPM and corresponding read/write speeds. Also, new Mass Storage Device drivers will have to be developed for Windows to take advantage of the spec.


The USB 3.0 A and B-side connectors

Uploads and downloads are kept on separate data lanes

Remember those five new lanes we mentioned earlier? With USB 3.0, two new lanes will be dedicated to transmit data, while another pair will handle receiving data. This not only accounts for the significant speed boost, but also allows USB 3.0 to both read and write at the same time from your portable storage device. In the old spec, the pair of lanes used for data transfer weren’t split between send and receive – they only could handle traffic in one direction. Bi-directional data transfer will be very useful for syncing up information on PDAs and storage backup.


The packed guts of a USB 3.0 cable — note that the cable will be about as thick as a ethernet cable 

USB 3.0 will charge more devices, quicker

Not only will USB 3.0 cables facilitate faster transfer speeds, but they’ll carry more power, too. The USB-IF recognizes the growing number of portable devices that charge via USB (cellphones, MP3 players, digital cameras), and have bumped the power output from about 100miliamps to 900 milliamps. That means not only will you be able to power more than 4 devices from a single hub, but the increase current will let you charge up heftier hardware as well.


USB 3.0 will be more power efficient

One of the mandates of the new spec is more efficient power-usage protocols. USB 3.0 abandons device polling in favor of a new interrupt-driven protocol, which means non-active or idle devices (which aren’t being charged by the USB port) won’t have their power drained by the host controller as it looks for active data traffic. Instead, the devices will send the host a signal to begin data transfer. This feature will also be backward compatible with USB 2.0 certified devices.


 A look at the mini connector that’ll connect to cell-phones and other portable devices

The spec that Intel released mid-last week is only 90% complete. Ravencraft says that they expect the spec to be finalized by Q4 of this year. Hardware partners are expected to have USB 3.0 controllers designed by mid 2009, and consumers won’t see the first end products utilizing the spec until early 2010 (though a late Holiday 2009 push for new products isn’t out of the question).