1) Find the Vendor and Device ID of the unknown device. To do this,
Open Device Manager
•(In windows XP :Start>Control panel>System>Hardware>Device Manager)
•(In Windows Vista:Start>Control Panel>Device Manager)
In Device manager,take the properties of unknown device
In Properties, click on Details tab and select Device Instance Id from the drop box.
You will see a code like this
HDAUDIO\FUNC_02&VEN_14F1&DEV_2C06&SUBSYS_104D1700&REV_1000
Here 14F1 is the Vendor ID
and 2C06 is the Device ID
Note: The code which comes after VEN is vendor ID & code which comes after DEV is device ID.
2)After obtaining both device and vendor ID, go to pcidatabase.com and search with your vendor ID or device ID to find the driver of the unknown device.
After finding your device model and manufacturer, you can either go to the manufactures website and download the necessary drivers or you can get them from these websites.
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