The Yamaha CBX Serial Driver is designed to provide access to external tone generator modules through the standard PC serial ports.
The driver can be used successfully under Windows 2000 without patches and running Service Packs 1 and 2.
Users who attempt to install the driver on a computer running Service Pack 3 may encounter a problem.
Editor's note: This article applies to Windows 2000 Service Pack 4 as well
Symptoms
The installer will proceed normally and at the end of the process prompt for the machine to reboot.
After rebooting, the list of drivers shown in the "Sounds and Multimedia" applet in the Control Panel appears unchanged.
Similarly, any sequencing software will also fail to find the new MIDI ports.
Despite these problems, the Control Panel will display the Yamaha CBX Driver applet and this works correctly.
Solution Background
The problem has been connected with a small but significant change in the registry.
The registry path affected is:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32
The following screenshot is taken from a computer running Windows 2000 Service Pack 2. It shows the first few values
under this key. Notice the entry midi1 that contains a reference to the file cbxt3usr.dll.
Fig 1. Windows 2000 SP2 with CBX Driver working correctly
Under Windows 2000 Service Pack 3, additional values have been placed under the registry path described above and this
can be seen in the comparison screenshot shown below.
Notice how "aux" and "midi" have values already created with suffixes between 1 and 9.
Fig 2. Windows 2000 SP3 prior to driver installation
After installing the driver and rebooting, an examination of the registry at this location reveals a new value "midi10" and the associated string "cbxt3usr.dll".
A typical registry would look like this:
Fig 3. Windows 2000 SP3 with a failed driver installation
Note: The previous screenshots are taken from a "clean" installation of Windows 2000 SP3. It is possible that you will have other MIDI devices occupying intermediate entries.
Solution Procedure
The registry state left by the installer needs to be modified so that the entry for cbxt3usr.dll is at a more appropriate
position.
On a clean installation of Windows 2000 SP3, this is likely to be in the midi1 position. Once again, if your installation
already has other MIDI drivers, it is possible that the new position will be at a higher numbered entry.
WARNING: Modifying the registry in an inappropriate manner can lead to erratic or potentially catastrophic problems with your computer. If you are not sure how to use the registry editor, leave this procedure to a more experienced colleague. Technical resources on the registry editor can be found at MSDN. You have been warned!
• Click on the Windows Start menu and select Run
• Type regedit and click OK
• Navigate to the registry key described in the solution background
• You should now see a list of values similar to Fig 3
• If midi1 is empty, double click it to display this dialog:
• Enter the text as shown above and click OK
• If midi1 is already occupied, double click the next available entry instead and modify
• Now RIGHT CLICK the midi10 value and select delete from the context menu.
• Confirm the deletion.
• The registry values should now look like this:
• Exit the registry editor
• Go to the start menu again and select Shutdown
• Choose the reboot option from the dialog and click OK
After rebooting, open the Control Panel and run the Sound and Multimedia applet. The following screenshot is typical of what you should now find.
