It's not very often that connection technologies make the news, but the arrival of Thunderbolt in Apple's new MacBook Pros has everyone asking crucial questions such as "what is it?", "how fast is it?" and "isn't that a terrible name for a kind of connection?"

So how does it compare with the other key interface standards, eSATA and USB 3.0?

Thunderbolt vs USB 3.0 vs eSATA: Speed

All three technologies are blazingly fast compared to USB 2.0, which tops out at 480Mbps.

eSATA delivers 3Gbps, with older eSATA 1.5 devices offering 1.5Mbps; USB 3.0, also known as Superspeed USB, goes up to 5Gbps; and Thunderbolt is a very respectable 10Gbps. As Intel puts it, that's enough to "transfer a full-length HD movie in less than 30 seconds".

Each Thunderbolt port is bi-directional and dual-channel, and devices can be daisy chained from a single connection. Potentially that means one device could be chugging data upstream at 10Gbps while another one sucks down data on the other channel at 10Gbps, although of course life is rarely that simple.

It's important to note here that these speeds are theoretical maximums, and there are all kinds of factors that will affect the speeds you actually get from connected devices.

Thunderbolt vs USB 3.0 vs eSATA: Compatibility

Thunderbolt combines two protocols, PCI Express (PCIe) and DisplayPort, which means you can connect monitors, external drives, video capture devices and so on. The DisplayPort element is backwards compatible, but you'll need a cable adaptor to connect an existing DisplayPort monitor.

USB 3.0 is backwards compatible, so you can connect USB 2.0 devices to a USB 3.0 hub and vice-versa, although of course you won't get USB 3.0 speeds.

eSATA is an external version of Serial ATA, the standard used for high-speed internal hard disk connections. As a result it's used for hard disks, hard disks and hard disks. Some firms, such as Toshiba, make laptops with dual-mode ports that can connect either eSATA or USB 2.0 devices.

eSATA

RARE SIGHT: Some firms such as Toshiba offer combined eSATA/USB 2.0 ports, but eSATA is still a relatively rare sight

Thunderbolt vs USB 3.0 vs eSATA: Availability

Right now, only one firm makes Thunderbolt-enabled computers - Apple - and Thunderbolt-enabled peripherals such as hard disks are just starting to be announced. USB 3.0 devices - largely, but not exclusively, hard disks - are already available, and there are plenty of eSATA hard disks out there too.

Thunderbolt is largely an Intel technology and Intel clearly favours it over USB 3.0, so we'd expect Thunderbolt's profile to change quickly as Intel chucks its considerable weight behind the technology.

LaCie and Western Digital are already on board, and as Thunderbolt is fairly simple to engineer - if firms are already making PCIe or DisplayPort devices, it's relatively easy to make them into Thunderbolt devices - we'd expect to see lots of firms follow suit.

Is that bad news for USB 3.0? Not necessarily. The ubiquity of USB 2.0 means there are lots of USB devices out there, and USB 3.0 is turning up in everything from laptops to tablets.

There are already stacks of USB 3.0 devices on sale, and the presence of LaCie and Western Digital in the USB 3.0 market as well as the Thunderbolt one suggests we're looking at USB and FireWire all over again, with consumer devices going for USB and pro kit using the faster, less common standard.

And eSATA? Its advantages over USB 2.0 are obvious, but even if it matched internal SATA's move to 6Gbps speeds it'd still be significantly slower than Thunderbolt and only slightly speedier than USB 3.0. It's starting to look like a technology whose time is almost up.

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Liked this? Then check out Intel Thunderbolt in Apple MacBook Pro explained

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