Using the FOR command then one can cycle through all drive-letters (A-Z), and for each partition that exists. It will find all the files which matches the mask given as input parameter.

Create a batch file FILEFIND.BAT with the following contents:

FOR %%D IN (C D E F G H I J K L M N O P Q R S T U V W X Y Z) DO IF EXIST %%D:\. DIR %%D:\%1 /S /P /A /B

Use the batch file like this to search for files with the extension ".DOC":

FILEFIND *.DOC