Comm.drv

Basics

Both Windows 3.1 and Windows 95 use a communications driver to handle the flow of data between Windows and the communications (COM) ports. Then default file used by Windows is called COMM.DRV (it is named the same for both Windows 3.1 and Windows 95, but they are different, incompatible drivers).

Third-Party Drivers

Some Windows 3.1 fax programs replaced the Windows communication driver with another one. Typically these were designed primarily for faxing and didn't support data communications well at 14.4 and almost no support for 28.8 or higher.

Usually these programs replaced the driver without prompting or notifying the user.

Determining What Driver Is Used

Windows 3.1

  1. In Program Manager, go to File--Run.
  2. In the command line, type in SYSEDIT.
  3. Go to the system.ini.
  4. In the first dozen lines should be one that starts with comm.drv. That's the communication driver that's being used.

Windows 95

  1. Go to Start--Settings--Control Panels.
  2. Double click on the Modems control panel.
  3. Go to the Diagnostics tab.
  4. Highlight the com port the modem is on.
  5. Click on More Info.
  6. Once the window comes up, make sure the ATI commands are reported. If they are, click on Ok.
  7. With the same com port highlighted, click on Driver.
  8. The window that pops up reports the driver used, the file size and the time and date of the file.

Changing the Driver

Windows 3.1

  1. In Sysedit in the system.ini, go to the beginning of the comm.drv line.
  2. Put a semi-colon (;) at the very beginning of the line.
  3. Go to the end of the line and hit Enter.
  4. On the new line type in comm.drv=comm.drv.

Windows 95

Theoretically, you could use the same method to change the communications driver in Windows 95. However, once this is done, Windows 95 may not be able to work with the modem. As a result, we cannot support changing the communications driver in Win 95.

Back to the Modem page