USB and FireWire explained
USB (Universal Serial Bus) and FireWire are two kinds of interfaces that let you transfer data between computers and peripherals with a specific type of cable. FireWire is the Apple term for IEEE 1394. Depending on which ports your Mac and peripherals support, your Mac may be able to connect to many different USB or FireWire devices, such as a printers, external hard drives, or digital cameras.
There are currently two USB specifications: The original USB version 1.1, and the newer USB 2.0. There are currently two FireWire standards: The original FireWire 400, and FireWire 800 (IEEE 1394b). In both cases, the higher number usually means faster data transfer rates.
FireWire is often found on devices that require very fast sustained data transfer rates, such as DV camcorders, audio interfaces, external hard drives, and professional scanners and printers. Note: Versions of iMovie earlier than iMovie 7 require a video camera with a Firewire connection. iMovie 7 and later support video cameras via USB or Firewire connections.
If you want to learn more about USB and FireWire ports and connectors, see USB: Descriptions of Ports, Connectors, and Cables or FireWire Ports: Specifications.
Which devices will work with my Mac?
First, check your Mac's ports. Most recent Macs have both USB and FireWire ports. To quickly verify what your Mac has, take a look at its ports—if you see a port stamped with an icon that looks like the left-most icon in the title graphic on this page, that's a USB port. (USB 1.1 and 2.0 ports look the same, and may support the same USB device, but you should check the USB device's packaging or documentation to be sure.)
If you see a port stamped with "Y"-like icon (to the right of the USB one shown above), that's a FireWire port. If you're not sure whether your FireWire ports are FireWire 400 or 800, you can look at the technical specifications for your product.
- Sample FireWire 800 port:
- Sample FireWire 400 port:
Tip: If you need to use a FireWire 400 device with a FireWire 800 port, or vice-versa, you might be able to use an adapter.
Second, make sure your Mac meets the device's requirements. USB and FireWire devices usually have their system requirements printed on the packaging, or you can generally find this information on the manufacturer's website. Be sure that your Mac meets the device's minimum system requirements—especially make sure that the device works with your installed version of Mac OS X.
Tip: To find out your Mac's processor speed, memory amount, and version of Mac OS, choose About This Mac from the Apple menu to bring up a window that displays this information.
Connecting devices to your Mac
Make sure you have the right cable: Most USB and FireWire devices require a cable to connect to your computer; a cable may have come with the device (some devices, such as a flash drive, can be plugged directly into a port).
If your device requires that you install software before using it, do so now and then restart your Mac. Then, simply plug your device into one of your computer's USB or FireWire ports using the appropriate cable (or make a direct connection).
Top troubleshooting tips
Use these suggestions if you encounter issues with the device.
- Check the connections
If you're using a cable, make sure that both ends of the cable are properly and securely connected to your device and Mac. Try unplugging your device and then plugging it back in. If you're connecting a FireWire device, make sure that the cable is no more than 15 feet (4.5 meters) long. If you're connecting a USB device, make sure that the cable is no more than 16 feet long. If you're making a direct connection, make sure that the device's connector is fully seated in your computer's port. If your device also connects to a power outlet, make sure it has power.
- Check the system requirements
Check your device's documentation or packaging again, or go to the manufacturer's website, to verify that your Mac meets the minimum system requirements to use the device.
- Check your device's power
If the device has a power switch, make sure it is on. Try turning your device off and then on again. Some devices require more power that the bus supplies. If your device came with an external power adapter, always connect it to a power source in for the best performance from your device.
- Restart your Mac
Sometimes a simple restart can resolve issues. From the Apple menu, choose Restart to restart your computer. Once your Mac is finished starting up, test your device again.
- Check the software
See if a newer version of software is available for your device if it requires software. Visit the product manufacturer's website.
- Check your device's power
Make sure that your device is on if it has a power switch; try turning your device off and then on again.
- Try a different port and cable
Connect your device to a different USB or FireWire port on your Mac. If you connected your device to a USB or FireWire hub or to a port on another USB or FireWire device that's connected to your Mac (known as daisy chaining), connect your device directly to a port on your computer. Some devices need to draw power from a USB or FireWire port to work; if you connect a device to a non-powered hub (one that isn't plugged in to a power source) or to a low-power port (such as the one on your USB keyboard), it may not work. If you have another known-good cable, try swapping the cable to see if that works. If it does, you should replace the problematic cable.
- Check for device conflicts
Disconnect all USB or FireWire devices (including hubs and extension cables) except for your Apple keyboard and mouse. Then, connect the device in question directly to your computer. If your device works now, there may be a conflict between that device and one of your other USB or FireWire devices. If it doesn't work, go to tip 8. If you do have a conflict, you can determine which devices are affected. Connect your other devices to your Mac, one by one, making sure to test that each device works before making another connection. When you find the device that causes the issue, contact the manufacturer for assistance (check both manufacturers' websites for software updates and additional information).
- Quit associated applications
If you're using a particular application that uses the device in question (for example, you're using Image Capture with a USB scanner), try quitting the application and then opening it again.
- Try another user account or computer
If you have another Mac available, try connecting your device to that other computer to see if it works. If you don't have another computer available, log in to another user account on your Mac (or create a new user account and log in to it), and test the device again. If the device is working now, there may be a software conflict between the device and something in your original user account.
- Check System Profiler for hardware Issues
Open System Profiler (from the Apple menu, choose About This Mac, then click More Info) and then click either USB or FireWire. If you don't see your device listed in the pane, the issue could be with the device itself or your computer's USB or FireWire port. To rule out the port, plug the device into another USB or FireWire port on your Mac and then check System Profiler again (press Command-R to refresh the window). Also try resetting the FireWire bus. If you see your device listed in the pane but it doesn't work, you may want to contact the device's manufacturer for assistance.
Still having issues?
If the tips above don't resolve your issue, here are some other things to try:
- Contact the device's manufacturer for assistance.
- Visit Apple Discussions and search for USB or FireWire to seek advice.