Multiple MPU-401 ports under Windows 3.11

[5u3]

Hi everyone,

I've come across an annoying little problem when using my MIDI synths under Windows 3.11: Apparently it is not possible to install more than one instance of the Roland MPU-401 driver. I already have it installed once for my LAPC-I (port 330H, IRQ 2/9), when I try to add the interface of my SCC-1 (port 332H, IRQ 3) the following message appears: "The required mpu401.drv driver is already installed on the system. Do you want to use the current driver or install a new driver?".

Microsoft's solution is not very helpful: "To use two Roland MPU401s, obtain a driver from the software package you are using to support them."

Is there any way around this?

P.S.: It is possible to change the port and IRQ of the installed driver to access the other interface, but that involves a lot of clicking and a Windows restart every time I want to switch.

[Great Hierophant]

I had a similar problem in Win 98.  The system would recognize both MPU-401s, but in practice would only allow me to use one, regardless of which I selected. 

[Locutus]

Hello 5u3,

my first idea would be to search through win.ini or system.ini. Somewhere in there ought to be a line, that says something like

Code:

midiN=mpu401.drv

N being a number that depends on how much other MIDI interfaces (AWE, GUS?) you already loaded.

You should try and copy that line, so that two instances of that driver are loaded, for example:

Code:

midi1=mpu401.drv
midi2=mpu401.drv

If that doesn't work because of the filenames being the same, you can try and copy one of the files to mpu401_2.drv or something.

You'll have to find out where the drivers keep their I/O port and IRQ settings. That will most possibly be stored in some INI file, I guess. So you'll have to figure out a way to configure both driver instances separately from each other. If the INI filename is hardcoded in mpu401.drv, you can get a hex editor and modify it. :-)

Those would be my approaches. I hope they help.

Regards,
locutus

[Ari]

I had a similar problem in Win 98.  The system would recognize both MPU-401s, but in practice would only allow me to use one, regardless of which I selected. 

I've never had any problems with getting 2 MPU-401 drivers to work simultaneously on win98.
Also, IIRC, it names the 2 devices differently: my LAPC-I is referred to as a "Roland MPU-401" device, and my SCB-55 (attached to a Roland MPU-401AT interface card) is referred to as a "MPU-401 out" device.

[5u3]

Thanks very much for the hints everybody, I figured it out now!

Yes, it is possible to have two MPU-401 drivers installed simultaneously, and it's actually quite easy to trick Windows into accepting them:
All you have to do is set up the standard Windows MPU-401 driver (MPU401.DRV) for one device and get the Roland driver (RDMPU401.DRV) for the other device. Both are very similar (they even have the same configuration interface), but they each run under different names and store their settings in different sections of SYSTEM.INI. Problem solved!

Here are excerpts from my SYSTEM.INI (for reference):

Code:

[drivers]

; Microsoft MPU-401 driver
Midi4=mpu401.drv

; Roland MPU-401 driver
Midi5=rdmpu401.drv

; SCC-1
[mpu401.drv]
port=332
int=3

; LAPC-I
[rdmpu401.drv]
ioport=330
intnum=2