Plug-and-Play Buses

The two most commonly used plug-and-play buses for connecting peripheral devices to Macintosh computers are Universal Serial Bus (USB) and FireWire. Bluetooth is less common, but is gaining popularity. Plug-and-play buses allow you to connect, use, and disconnect devices while the device and the computer are powered on (hot-swapping), without the need to install special drivers or software for the devices to function.

USB 1.1/2.0

Universal Serial Bus (USB) is a plug-and-play interface for external add-on devices such as audio players, joysticks, keyboards, phones, scanners, and printers. You can connect USB devices directly to your computer or to other USB devices. For example, you can connect your USB mouse to your USB keyboard, which is then connected to your computer. You can also purchase USB hubs that allow you connect several USB devices to a single port on your computer.

USB 1.0/1.1 is the original version of the USB specification, still in use in many environments where maximum data transfer is not needed. Its maximum speed is 12 Mbit/s. The most recent USB version, USB 2.0, supports data transfer speeds of up to 480 Mbit/s, and is better suited for high-speed peripherals, such as storage devices and digital cameras. USB 2.0 devices can be plugged into a USB 1.1 port, but the device will operate at the slower bus speed. Also, USB 1.1 devices can be plugged into a USB 2.0 bus, but that will force all devices on the bus to operate at the slower speed.

USB devices operate at three speeds. High-speed devices are designed for a data rate of 480 Mbit/s. Full-speed devices are designed for a data rate of 12 Mbit/s. Low-speed devices are designed for a data rate of 1.5 Mbit/s. High-speed and low-speed devices can both operate at their rated speed as long as the bus version is the same. Whenever possible, segregate USB devices by bus version.

While USB ports provide power, the maximum power is very low (5 volts and .5 amps). While a low-power device, such as a mouse or keyboard, can be plugged into any USB port, a device that requires more power, such as a scanner, needs to be plugged into a powered port directly on the computer or on a powered USB hub. A self-powered USB device requires its own separate power supply.

USB Error Messages

Most USB issues occur because a device is not properly powered or the correct driver software is not installed. There are four categories of USB error messages:

• Not Enough Power to Function A device is drawing too much power, or the device requires its own power cord.

• Not Enough Power for All Functions There is enough power to supply some, but not all, of the functions the device is designed to provide.

• The USB Driver Needs to be Updated. Would you like to search for the update on the Internet? Mac OS X detects an out-of-date driver.

• No Driver Found Mac OS X detects no driver for the device, and cannot use the generic driver for the device class.

Troubleshooting USB Issues

To troubleshoot USB issues, try the following:

• Make sure all USB cables and power cords are plugged in properly.

• Make sure you have installed any software that was included with the device. Check for updates to software required by the device. Visit the manufacturer's website to get the latest software for your device.

• If the device doesn't have a power cord and is plugged into another USB device that doesn't have a power cord, try plugging the device directly into your computer or to a USB device that does have a power cord.

FireWire 400/800

All current Macintosh computers have one or more FireWire 400 (IEEE 1394a) ports that transfer data at up to 400 Mbit/s. Some also have a FireWire 800 (IEEE 1394b) port that transfers data at up to 800 Mbit/s.

FireWire ports can provide bus power to FireWire devices (more power than USB; up to 30 volts and 1.5 amps). This is enough power to operate webcams, hard drives, or other devices; if your device can run on bus power, it does not need a separate AC adapter.

FireWire devices have 4-pin, 6-pin, or 9-pin connectors. The 4-pin connectors do not provide bus power, but are popular on digital video cameras due to their compact size. On Macintosh computers, FireWire 400 ports have 6-pin connectors, and FireWire 800 ports have 9-pin connectors. You must use a FireWire cable that has the correct connector for your computer on one end, and the correct connector for the device on the other end. So if you have a device with a 4-pin connector and you want to plug it into your computer's FireWire 400 port (which accepts a 6-pin connector), you need a 4-pin to 6-pin cable.

MORE INFO

Visit http://developer.apple.com/devicedrivers/firewire/index.html or refer to Knowledge Base document 30520, "About FireWire 400 Technology."

Starting in Target Disk Mode

Most Mac OS X computers that have built-in FireWire have the capability to start in Target Disk Mode (TDM). Instead of booting the operating system, the computer (target) in disk mode acts as a hard drive that can be used by the host Macintosh with a FireWire connection. Essentially, this gives the host computer full access to the master internal hard drive of the target computer.

NOTE

Blue and White G3 computers do not support Target Disk Mode.

Target Disk Mode is useful whether or not the computer can boot. You may opt to use TDM on a fully-functioning computer as an alternative to file sharing over a network if you have a large amount of data to transfer between computers. You can also use Target Disk Mode to migrate user accounts and home folders from one computer to another using the Migration Assistant during setup. You can even install software on a computer in TDM (for example, to get around Mac OS X 10.4's requirement for a DVD drive).

Target Disk Mode is especially useful when a computer is unable to boot. You can use TDM to try to fix the problem with Disk Utility or third-party tools running on another computer. If that fails, you may still be able to copy or recover files from the nonbooting computer before erasing.

Target Disk Mode can be a big security risk. There are multiple ways to use TDM to access a system without knowing the system's password. If someone has physical access to a system, he or she can access files on the system. One method to lock out TDM is to use the Open Firmware Password utility (which you can download from Apple) and give the hardware itself a password.

To experiment with Target Disk Mode, you need two Macintosh computers with FireWire ports and a single FireWire cable. If you don't have access to the necessary hardware, you can still follow along with these instructions:

MORE INFO

Refer to Knowledge Base document 58583, "How to Use FireWire Target Disk Mode."

1.	Unplug all other FireWire devices from the target computer (the one whose hard drive you want to access) prior to using Target Disk Mode. Do not plug in any FireWire devices until after you have disconnected the two computers from each other, or have stopped using Target Disk Mode.
2.	Shut down the target computer.
3.	Start up the target computer and immediately press the T key until the FireWire logo appears, indicating that the target computer is now in Target Disk Mode. NOTE Startup Disk preferences in Mac OS X 10.4 has a new Target Disk Mode button that restarts the computer in TDM. NOTE If you are using a laptop as the target computer and battery power becomes completely drained during this process, disk corruption can occur. For this reason, it's highly recommended to use an AC adapter when in Target Disk Mode.
4.	Make sure the host computer is fully booted into the Finder in Mac OS X.
5.	Connect the target computer and the host computer using a FireWire cable. After a few seconds, Mac OS X adds the target computer's hard drive to the Sidebar. In some cases, the hard drive may not appear right away because the operating system may be busy verifying the disk.
6.	Use the target computer's hard drive as you would any other volume.
7.	When you are done with the target computer's hard drive, unmount it by selecting its icon in the Finder and choosing File > Eject (Command-E).
8.	Disconnect the FireWire cable from the host computer and the target computer.
9.	Press and hold the power button to turn off the target computer.
10.	Turn on the target computer without pressing any keys at startup to return it to normal operation.

Troubleshooting FireWire Issues

To troubleshoot FireWire issues, try the following:

• Make sure each FireWire device is turned on and connected to AC power (if device is not bus-powered).

• Make sure all cables and power cords are plugged in. Make sure the cables match the requirements for the FireWire connection protocol (for FireWire 400, cables no longer than 15 feet; for FireWire 800, cables no longer than 300 feet).

• Make sure you have installed any software that came with the device. Check for updates to software required by the device. Visit the manufacturer's website to get the latest software for the device.

• If the device still doesn't work, try quitting and restarting any applications that use the device.

Bluetooth

Bluetooth is a short-range wireless connection protocol used by desktop and portable computers, personal digital assistants, mobile phones, printers, scanners, digital cameras, and even some home appliances. It uses a globally available frequency band (2.4 GHz) for worldwide compatibility. Because Bluetooth uses a radio frequency to transmit data, Bluetooth devices communicate with any devices in range, even those that are not in line of sight. Although Bluetooth uses the same frequency as AirPort, they can both be enabled at the same time.

With Bluetooth, you can link your Palm OS-based handheld device, Bluetoothenabled mobile phone, and other peripherals to your Bluetoothequipped computer within a 30-foot range. Once linked, you can synchronize data, such as contacts and schedules, between your Macintosh and Bluetoothenabled mobile phones and PDAs, or even use your Bluetoothenabled mobile phone as a wireless mobile modem. While Bluetooth is not intended as a replacement for AirPort, it can be used for simple computer-to-computer communication. Mac OS X includes the Bluetooth File Exchange application (/Applications/Utilities) to transfer files between two Bluetoothenabled computers.

To use Bluetooth, you must either have a computer with Bluetooth preinstalled or install a Bluetooth adapter, such as the D-Link DWB-120M Bluetooth USB adapter. You can use Bluetooth preferences to pair up with a device configured to be discoverable and set a passkey to authenticate connections with the device. Bluetooth preferences presents a list of all Bluetooth devices within range that are configured to be discoverable. Once you select the Bluetooth device in the list and click the Pair button, you're connected.

Configuring Bluetooth Preferences

To experiment with Bluetooth devices, you need two Macintosh computers, both with built-in Bluetooth or with Bluetooth adapters. If you don't have access to the necessary hardware, you can still follow along with these instructions.

Before you can use Bluetooth to connect your computer to another Bluetooth device, you must perform some configuration, including setting a unique name for your computer:

1.	Log in to your computer as Apple Admin.
2.	If you are using a computer that does not have built-in Bluetooth support, plug a Bluetooth USB dongle into a free USB port.
3.	Open System Preferences. You should see a Bluetooth icon in the Hardware section.
4.	If you do not see the Bluetooth icon, quit System Preferences and reopen it.
5.	Click the Bluetooth icon to open Bluetooth preferences.
6.	Click the Settings button. The Bluetooth Device Name is the computer name set in Sharing preferences. Bluetooth preferences include the option to open the Bluetooth Setup Assistant automatically when you start your computer and a cabled keyboard and mouse are not detected. This allows you to configure a computer that shipped from the factory with a Bluetooth keyboard and mouse, for example.
7.	If Bluetooth Power is off, click Turn Bluetooth On.
8.	Select "Show Bluetooth status in the menu bar." This adds a Bluetooth menu extra at the right of the menu bar.
9.	If it is not already enabled, select the Discoverable checkbox.
10.	Repeat steps 1 through 9 on a second Bluetoothcapable Macintosh, making sure that it has a unique computer name set in Sharing preferences.

Exchanging Files Using Bluetooth

To use the Bluetooth File Exchange application to exchange files between Bluetoothenabled computers, follow these steps:

1.	In Bluetooth preferences on your computer, click Sharing. The Sharing pane determines how files are transferred using Bluetooth. Use the defaults for this exercise.
2.	From the Bluetooth menu extra, choose Send File.
3.	Select a small sample file on your computer, then click Send. The Bluetooth File Exchange application opens and displays the Send File window listing previously-paired devices.
4.	Click Search to find the Bluetoothenabled computers within range. You might have to click the Search button multiple times to find your other computer. By default, your computer will accept single file transfers in this manner, unless you turn off Discoverable access for Bluetooth or deselect Bluetooth File Exchange in the Sharing pane of Bluetooth preferences.
5.	Select the name of the computer you want to send files to from the list, and then click Send. A dialog will appear while Bluetooth File Exchange negotiates the transfer and waits for acceptance.
6.	On the receiving computer, click Accept to receive the file. If you select the "Accept all without warning" checkbox, all files sent via Bluetooth will automatically be placed in your Documents folder.
7.	When the file transfer is completed, the receiving computer displays a dialog listing the file transferred.
8.	Click the Find button (the magnifying glass) to open the folder containing the sent file. NOTE The default location for accepted items is specified in the File Exchange pane of Bluetooth preferences.
9.	Quit Bluetooth File Exchange.

Pairing Two Devices Using Bluetooth

When you want two devices to communicate automatically, they must be paired so they can identify and authenticate each other. Normally you would pair your computer with a Bluetooth device such as a phone or PDA; however, this exercise has you pair two computers. The task is very similar to pairing with a phone or PDA.

1.	On your computer, click Devices in Bluetooth preferences.
2.	Click "Set up new device." The Bluetooth Setup Assistant prompts you for the device type.
3.	Select Other Device, and click Continue. Bluetooth searches for Bluetoothenabled devices within range. At first all other in-range Bluetoothenabled devices are displayed as their MAC addresses, but after a few seconds, these numbers are replaced with their DNS names or local hostnames.
4.	Select the device (your other computer) that you want to pair with, and click Continue. You will see a six-digit passkey on your computer while a pairing request dialog appears on the other computer.
5.	On the other computer, enter the passkey and click Pair. If you enter an incorrect passkey, no error appears, and you will have to try again. If you enter the correct passkey, the Bluetooth pair is created and remembered, and the paired computers appear in each other's Bluetooth Devices lists in the Devices pane.
6.	On the other computer, the Devices pane of Bluetooth preferences should look something like this: You have established a secure connection to a known device. Note that the device address is visible in this dialog, along with the device name.
7.	Quit Bluetooth preferences. Paired devices and computers will automatically attempt to connect to your computer if they are within range of the Bluetooth receiver. Therefore, pairing allows devices such as PDAs, mobile phones, keyboards, and mice to work seamlessly with your computer, and you can delete specific pairings or create temporary pairings as needed.