While VMware's ability to run numerous virtual machines off of a single physical device is handy, hardware-based services like connecting a USB device to the virtual machine can seem tricky at first blush. While connecting a real, physical device to a completely virtualized computer may seem impossible, VMware actually includes the functionality as part of its Workstation suite, and can support USB devices quite easily.

USB Controller

VMware's Workstation software features a USB controller system for both USB 1.1 and 2.0 devices, enabling virtual machines to use USB resources connected to the host computer. While most devices are supported as long as the host computer has the appropriate drivers, there are some that don't work properly with VMware. These include speakers, webcams, modems and other streaming data devices.

Connecting USB Devices

Connecting USB devices to a virtual machine in VMware rarely requires additional configuration. The device is automatically detected by and connected to the virtual machine, as long as the virtual machine is running and its window is active when the device is plugged in; if not, the device connects to the host computer instead. You can select any connected USB devices and connect them to the virtual machine manually by plugging in the device, clicking "VM," selecting "Removable Devices," selecting the device from the list, and then clicking "Connect." Note that devices connected via a USB hub are detected individually.

Ejecting USB Devices

To eject a USB device from the virtual machine, click "VM," select "Removable Devices," and then click "Disconnect" after selecting the device from the list. Before you disconnect the device, however, make sure to set it to a safe ejection state following the manufacturer's instructions. Set the device to this ejected state whether you're completely disconnecting the device, or only switching between virtual machines or the virtual machine and the host computer. Doing so prevents damage and data loss when using a USB storage device.

Human Interface Devices

USB interface devices like a keyboard and mouse are handled differently by the VMware virtual machine. They aren't managed in the USB controller, and instead are read by the virtual machine as being connected via PS/2 connectors. This frees up virtual USB ports for more devices to be connected to the host computer and the virtual machine.