1.1 NetBIOS and DOS: The Early Years

Starting with DOS version 3.1, Microsoft used the NetBIOS API to transport SMB file service messages. They created something called a redirector , and its job was to catch disk drive or port references (e.g. " C: " or " LPT3: ") and look them up in a table. If the device was not in the table, the call was passed along to DOS. If the device was in the table, then the call would be redirected . For example:

• Using the SUBST command, a user could substitute a drive letter for a local path . This simple aliasing provided convenient shortcuts for long path names :

   subst S: C:\FILES\DEEP\IN\A\DIRECTORY 

• Using the NET command, a drive letter could be mapped to a remote file service. So, if the redirector found a remote service entry in its table, it would convert the request into an SMB packet and send it out via NetBIOS:

   net use N: \SERVER\SERVICE 

  Note the double backslash preceding the server name . This syntax is part of Microsoft's " U niversal N aming C onvention" (UNC) for network services.

These commands are still available from within the DOS shells of contemporary Windows products. It is worthwhile to fiddle with them a bit. At the DOS prompt, you can type NET HELP for a summary of the NET command and its options. ^[1]

^[1] ...or, if you type the way I do, you can enter NEWT KELP to generate an error message.