Microsoft is incorporating a software stack in its upcoming Windows 8 OS to natively support devices based on the USB 3.0 interconnect, which is in a battle for adoption with Intel's Thunderbolt.
USB 3.0 is the successor to USB 2.0 standard and can transfer data 10 times faster between computers and external peripherals such as cameras and storage devices. Most laptops and desktops today come with USB 2.0 ports and many PC makers are offering USB 3.0 ports as an option. The current Windows 7 OS does not include native support for USB 3.0, but device makers offer drivers to ensure products are compatible with the OS.
The growing support for USB 3.0 and wide usage of USB 2.0 was a compelling reason to improve the USB software stack, said Dennis Flanagan, Microsoft's director of program management for the devices and networking group, in an entry on the company's Building Windows 8 blog.
"By 2015, all new PCs are expected to offer USB 3.0 ports, and over 2 billion new 'SuperSpeed' USB devices will be sold in that year alone," Flanagan wrote.
Microsoft is writing a new software stack and controller for Windows 8 based on the "design principles" of USB 3.0, which will bring plug-and-play support for new devices such as external storage, webcams and keyboards, Flanagan wrote. The company is retaining the existing software stack to support older USB devices.
But there are few USB 3.0 devices available today, so to create the new software stack the company had to simulate and build virtual USB 3.0 hardware, including ports, hubs and devices.
The hardware support for USB 3.0 is also growing. Intel has already said it will integrate USB 3.0 support in chipsets for processors code-named Ivy Bridge, which will reach PCs early next year. AMD has already integrated support for USB 3.0 in its Fusion chipsets, which are already shipping for PCs.
USB 3.0 transfers data at speeds of up to 5 gigabits per second, which is slower than the transfer speed of rival interconnect technology Thunderbolt. Developed by Intel, Thunderbolt can transfer data between host computers and external devices such as displays and storage at up to 10 gigabits per second. Thunderbolt has been viewed as an alternative to USB 3.0, but Intel has the said the technologies are complementary. Apple uses Thunderbolt in its products.
Thunderbolt currently supports the PCI Express and DisplayPort protocols, and the interconnect does not require any OS support beyond existing software stacks for those protocols, an Intel spokesman said in an e-mail.
But Microsoft's backing will aid the fast growth of USB 3.0 and provide higher transfer speeds for consumer devices, said Jim McGregor, research director at In-Stat.
"Thunderbolt will be one of many peripheral options available, just like IEEE1394 and Firewire, but I think USB will be the predominant interface because it is so heavily tied to the largest growth segment of the market, mobile devices, for both interconnectivity and power," McGregor said.
Thunderbolt is based on copper wires, but ultimately will be based on optical technology. That will boost the interconnect's transfer speed and distance, Intel has said.
"[USB 3.0] will still not be as fast as the Thunderbolt optic link, but copper never will be as fast as optics," McGregor said.
Wireless charging could trump both USB 3.0 and Thunderbolt, provided it takes off, McGregor said. The transfer speeds may not be as fast, but device makers are showing interest in the technology, he said.
"It may eventually eliminate the need for peripheral connectors on mobile devices and then everyone will look to wireless interfaces," McGregor said.
Other than enthusiast users, drivers aren't something average PC users need to worry about, but native support for USB 3.0 in Windows 8 can't hurt, said Nathan Brookwood [CQ], principal analyst at Insight 64.
"When they are talking about the history of Windows 8, they are going to be talking about the user interface and ... touch," Brookwood said.