Correcting the Windows MIDI Device Limit Issue
When Windows XP has installed over a certain number of MIDI devices, it will refuse to show any new ones
until you delete some of the existing ones. The catch? Windows considers ANY device you've ever connected
to be a valid installed device, and it won't show you these installed (although currently unused) MIDI devices
in the Device Manager EVEN IF you select the 'Show hidden devices' option.
Fortunately there is a way to force Windows to be honest with you, but it involves writing a key to your
NOTE: Editing your registry requires great care - You could prevent Windows from running correctly if you
make any mistakes. Psicraft Designs and/or TC Electronic will not be responsible if you damage your windows
installation while following these instructions, so take care or have a qualified friend perform the operation if
Here is how you can check your Windows XP machine out to make sure your issues are not because of the
device limit being reached: First, unplug your MIDI Interface’s USB cable from the computer, then follow
these 10 steps...
Before you proceed, make sure to back up the registry, and make sure that you understand how to restore
the registry if a problem occurs. See http://support.microsoft....x?scid=kb;EN-US;256986
(Microsoft Knowledge Base article 256986) for more information.
Steps 3-6 are optional, and are for your safety.
1. Click on the Start menu, then select Run.
2. Type in regedit and click OK.
3. Click on the File menu, and select Export.
4. Set the directory where you are saving the registry file to your Desktop.
5. Type in any name for the file, and make sure All is selected.
6. Click SAVE, and verify that it has created a backup file on your desktop.
7. Navigate to the System Key called:
8. If there is an entry called DEVMGR_SHOW_NONPRESENT_DEVICES already there, make sure its
value is set to 1. If the value is missing from within the Key, Right-Click over the listing and select
NEW->String Value from the pop-up menu.
9. Rename the new REG_SZ (String Value) to DEVMGR_SHOW_NONPRESENT_DEVICES and set
its value to 1. (1 = show all hidden devices, incidentally).
10. Exit regedit and restart your computer.
11. On restart, open your control panel, select the system icon, select the Hardware tab in the
System Properties dialog and then press the 'Device Manager' button. Now for the magic part:
Open Device Manager's View menu and check the 'Show hidden devices' option.
12. With the new registry key in place, Device Manager will actually do something for a change when this
option has been checked. You can now click on the 'Sound, video and game controllers' icon and
you'll see all the ghost MIDI and Audio interfaces that windows has installed.
13. Delete any ghosted out 'USB Audio Device' icons you see. If you see any MIDI interface drivers for
hardware you no longer own, feel free to delete these too. If you delete a ghosted driver for hardware
you still own, this will not cause any harm except to require you to reinstall the drivers the next time
you connect that MIDI device.
14. For good measure, click on the 'Universal Serial Bus controllers' icon and delete any ghosted USB
Composite devices you see (especially if there are lots of them): This will require that Windows
reinstall drivers the next time you reconnect some of your less used peripherals, but this should not
be a problem.
15. Make sure that any Logitech web-cam drivers are not hanging around in ghost form! Delete them if
you find them.
16. Now reboot and reconnect your USB MIDI Device. Once Windows informs you the device is ready to
use, launch Vyzor and see if the interface’s MIDI in ports are now available.
This concludes the Vyzor G-System Troubleshooting PDF Manual. It’s a good idea for you to also read
the companion PDF manuals like the Vyzor G-System Quick-Start, Vyzor G-System User’s Guide and
Data Management with Vyzor G-System for a more complete view of how the editor operates. Just as
with this PDF, these PDF files are also accessible from the program’s Manuals pull down menu.
post edited by John - 2010/01/20 09:34:37