Testing Dual Rank 0 and 1 Entries

It is important to determine whether there is a modem INF file that uses your modem ID string in a Rank 0 position, search all the Mdm*.inf files in \Windows\Inf for your modem ID string, using a Grep-like tool. You must make sure that your modem ID string is unique before you use it as a Rank 0 ID in your INF. If you find your modem ID is being used as a Rank 0 ID in another modem INF, you must use your modem ID as a Rank 1 ID.

If you decide to use a Rank 1 modem ID string in your INF file, you may have to do some extra work when you test your INF file with Windows 95. If there is a modem INF file in the \Windows\Inf subdirectory that uses the same modem ID as a Rank 0 ID, use the following procedures to guarantee you test the installation of your modem with both INF files. Different procedures are used for non-Plug and Play modems as opposed to Plug and Play or PCMCIA modems.

Installing and Testing Non-Plug and Play Modems

Suppose your INF file is named MDMMINE.INF and contains the following Rank 1 entry:

   %Modem1% = Modem1,,  UNIMODEMD9C98361

Suppose also that you found another INF file in \Windows\Inf named MDMOTHER.INF that contains the following Rank 0 entry:

   %Modem13% = Modem13,  UNIMODEMD9C98361

You must install and test your modem with both of these INF files. You can do this by turning the auto-detection feature on and off in the Add New Modem wizard dialog.

To run the Add New Modem wizard, select Start:Settings:Control Panel and double-click the Modem icon. On the Modem Properties panel, click the Add button. That starts the Add new Modem wizard. On the first wizard dialog box, you can toggle the auto-detection feature using the check box labeled "Don't detect my modem; I will select it from a list."

Continuing with the two example INF files for non-Plug and Play modems, MDMMINE.INF (which has the Rank 1 entry) and MDMOTHER.INF (which has the Rank 0 entry), use the following procedure to test both INF files:

To install your modem using MDMOTHER.INF, use the Add New Modem wizard with the check box turned off (unchecked).
When you done testing the MDMOTHER.INF installation, remove your modem from the Control Panel.
To install your modem using MDMMINE.INF, use the Add New Modem wizard with the check box turned on (checked) and then test that installation.

Testing PCMCIA and Plug and Play Modems

Suppose your INF file for your PCMCIA modem is named MDMMINE.INF and contains the following Rank 1 entry:

   %Modem1% = Modem1,,  PCMCIA\GENERIC__-14.4_MODEM/FAX_-D900

Suppose also that you found another INF file in \Windows\Inf named MDMOTHER.INF that contains the following Rank 0 entry:

   %Modem4% = Modem4,  PCMCIA\GENERIC__-14.4_MODEM/FAX_-D900

This sort of thing can happen if you and another manufacturer are OEMs using a PC card chip set from the same chip set manufacturer and neither OEM changes the tuples the chip set manufacturer built into the PC card. If you do not (or cannot) change the tuples on your PC card, then you must install and test your modem with both of these INF files. Unlike non-Plug and Play modems, you cannot do this by turning the auto-detection feature on and off in the Add New Modem wizard dialog. Here is the procedure to use for PCMCIA cards:

Physically install your PC card modem and start the system; this will cause Windows 95 to install your modem using MDMOTHER.INF (which has the Rank 0 modem ID).
When you are done testing your modem with the MDMOTHER.INF installation, edit MDMOTHER.INF and change the Rank 0 entry to a comment by putting one or more semicolons in front of the entry.
For example, change the Rank 0 entry from
```
   %Modem4% = Modem4,  PCMCIA\GENERIC__-14.4_MODEM/FAX_-D900
 
```
to
```
   ;;%Modem4% = Modem4,  PCMCIA\GENERIC__-14.4_MODEM/FAX_-D900
 
```

Next, edit the Rank 1 entry in MDMMINE.INF to change it to a Rank 0 entry.

For example, change the Rank 1 entry from

   %Modem4% = Modem4,,  PCMCIA\GENERIC__-14.4_MODEM/FAX_-D900

   %Modem4% = Modem4,  PCMCIA\GENERIC__-14.4_MODEM/FAX_-D900

With your PC card modem physically installed, restart the system. This will cause the system to install your modem using MDMMINE.INF.
When you are done testing the MDMMINE.INF installation of the modem, edit the two INF files to restore the original Rank 0 and Rank 1 entries.

If your modem is a Plug and Play modem (ISAPNP or SERENUM) and you use a Rank 1 modem ID, the probability you will find a modem INF file in the \Windows\Inf subdirectory that uses the same modem ID in a Rank 0 entry is quite low. However, you must always check for the possibility using a Grep-like tool. If you do find such a case, to test both INF files use the same procedure that is shown in the preceding for PCMCIA modems.