1) Open the Device Manager

2) Double-click on "MPU-401". 

3) Click on Resources, and remove checkmark from the Use Automatic 
   Settings checkbox.

4) Change the Basic Configuration to 0001.  The Resource Settings window 
   will now show an Input/Output Range, and an Interrupt Request.  

5) Make sure nothing is conflicting before you continue. 

6) Close the Device Manager, and shut down the computer fully, with 
   Start Menu | Shut Down | Shut Down the Computer.  Turn the power off.  

7) Leave the computer off for a couple of seconds, then power it back on. 
   You should now have MIDI input as well as output.

Note:  This is only required with drivers version 1.3 and above. 
       The interrupt is used only as a clock for recording MIDI in, 
       so it's not required if you aren't recording.

If the MPU-401 is in Basic Configuration 0001 already, you will need to 
check some other basic things:

* Is the sequencing program set up correctly to record data from the proper 
  inputs (TBS-2000 ext. in) ? 

* Are the cables attached correctly (computer output to keyboard input, 
  computer input to keyboard output) ?

* Is the IRQ available?  If any conflicts are shown, try a different IRQ.  

* Is the I/O range available?  If not, try a different I/O.