USB Products

General frequently asked questions about USB Products

1. Do USB 1.1 cables work with USB 2.0 devices?
2. Do USB 2.0 & USB 1.1 hardware work interchangeably?
3. How will I benefit from USB 2.0?
4. I would like more information about USB technology?
5. What do I need to use a USB 2.0 device?
6. What happen if a USB 2.0 device is plugged into a USB 1.1 system?
7. What is the difference between USB 1.0, USB 1.1 and USB 2.0?
8. What is the max. length of a USB 2.0 cable?
9. What is USB?
10. Will USB 1.1 devices run any faster on a USB 2.0 bus?
11. Will USB 2.0 replace USB 1.1?

1. Q : Do USB 1.1 cables work with USB 2.0 devices?

A : Ideally, yes. USB 2.0 architecture uses the same cables and connectors as USB 1.1 compliant products. (Return to Top)

2. Q : Do USB 2.0 & USB 1.1 hardware work interchangeably?

A : You may have heard that USB 2.0 is "backward-compatible" with USB 1.0/1.1 (Full-Speed USB). While that's true, USB 1.1 is also forward-compatible with USB 2.0. Whenever a system has USB 2.0 ports, you'll find the "Enhanced" USB controller in Device Manager, but you will also find two other USB controllers. These two to mantain backward compatibility to USB 1.1 devices. Each USB 2.0 host actually has 3 chips onboard. The USB controller routes signals to the correct controller chip depending on how a device is recognized. Where a device is physically plugged in has no bearing on how it is routed. All ports on a USB 2.0 motherboard can host any USB devices at all as long as the system and devices are healthy.

The vast majority of USB 2.0 devices will work on older PCs and Macs. None should flat-out fail unless there are other issues with the system. Hi-Speed USB devices will revert to Full-Speed operation when connected this way. Understand that Hi-Speed is at least ten times faster than Full-Speed in actual operation, so the speed difference is quite noticeable? unless you have never experienced Hi-Speed, of course. (Return to Top)

3. Q : How will I benefit from USB 2.0?

A : With speed 40 times more than that of USB 1.1, USB 2.0 broaden the range of external peripherals that can be used on a computer. Even with multiple high-speed peripherals connected to a USB 2.0 bus, the system will less likely to hit the bandwidth bottleneck. The new specification also inherits the current USB's Plug and Play and hot-swapping capability as well as providing backward compatibility for USB 1.1 hardware, allowing existing user base to upgrade seamlessly.(Return to Top)

4. Q : I would like more information about USB technology?

A : If you need a more technical explanation on the technology or its development, please visit http://www.usb.org (Return to Top)

5. Q : What do I need to use a USB 2.0 device?

A : The requirement is similar to that of USB 1.1, but all components will have to be USB 2.0 compliant. A successful USB 2.0 connection requires a USB 2.0 host controller card, a USB 2.0 driver and a USB 2.0 peripheral .(Return to Top)

6. Q : What happen if a USB 2.0 device is plugged into a USB 1.1 system?

A : The entire bus under the USB 1.1 root hub will slow to 12Mbps. The operating system will probably notify the user about the sub-optimal configuration and recommend for a better course of action.

If several USB 1.1 hubs are connected to a USB 2.0 bus, then each of the USB 1.1 hub will get a full 12Mbps bandwidth.

7. Q : What is the difference between USB 1.0, USB 1.1 and USB 2.0?

A : USB 1.0 can operate at 1.5 Megabits per second (Mbps).

USB 1.1 allowed a maximum transfer rate of 12Mbits/second. USB mice and keyboards need only 1.5Mbits/s to function. That performance level is also named 'USB'.

USB 2.0 has a raw data rate at 480Mbps, and it is rated 40 times faster than its predecessor interface, USB 1.1, which tops at 12Mbps. Originally, USB 2.0 was intended to go only as fast as 240Mbps, but then, USB 2.0 Promoter Group increased the speed to 480Mbps in October 1999.

You can use USB device with USB 1.0, USB 1.1 and USB 2.0 as long as your PC or laptop has USB ports, but USB 2.0 device transfer data at 480 Mbps on systems with USB 2.0 support only .(Return to Top)

8. Q : What is the max. length of a USB 2.0 cable?

A: 5 meters. However, if you cascade 5 hubs with 5m USB cables, this will allow you to connect a device 30m away. (Return to Top)

9. Q : What is USB?

A : Universal Serial Bus, or USB

This competing serial input/output technology was introduced in 1997. USB ports are found on most desktop PCs, notebooks, and peripherals today. There are far more USB devices than there are FireWire peripherals. The new USB 2.0 specification promises data transfer rates of 480 mbps, which is 80 mbps faster than FireWire. USB 2.0 devices are backwards-compatible with USB 1.1 ports. While you won't get the increased speeds, you can use a USB 2.0 device with your current notebook's USB 1.1 port. (Return to Top)

10. Q : Will USB 1.1 devices run any faster on a USB 2.0 bus?

A : No. However, the new USB 2.0 archiclecture allows more high-speed USB 1.1 devices, such as webcams, audio devices, to share the bandwidth. Developers need to follow USB 2.0 spec in order to design higher speed peripherals that can take advantage of the extra bandwidth. USB 1.1 devices still operate at 12Mbps at full-speed and 1.5Mbps at low-speed on a USB 2.0 bus. Even though USB 1.1 devices won't run any faster, they can work alongside of USB 2.0 devices on the same bus. (Return to Top)

11. Q : Will USB 2.0 replace USB 1.1?

A : Not entirely, because many products such as generic keyboards, mice, joysticks and audio speakers do not require the faster speed of the new USB 2.0 technology. Only bandwidth-hungry devices, such as webcams and high-capacity storage systems, will need all the speed. However, next-generation systems will come with USB 2 ports rather than USB 1.1.