Using SYSTEM.INI's COMMDRV30 Switch (82789)
The information in this article applies to:
- Microsoft Windows 3.1
- Microsoft Windows 3.11
This article was previously published under Q82789 SUMMARY
This new switch for the Microsoft Windows operating system version 3.1
indicates to the Virtual COM Device Driver (VCD) that it needs to configure
itself to handle hardware interrupts for COMM.DRV in the same manner as in
Windows 3.0. This switch is needed only if you are using enhanced mode and
have a third-party COM driver, but don't have a replacement VCD.
MORE INFORMATION
In Windows 3.0's enhanced mode, the VCD is responsible for handling the COM
port hardware interrupts for COMM.DRV, and thus Windows applications. In
Windows 3.1, COMM.DRV handles its interrupts directly; therefore, the VCD
can be smaller because it doesn't have to duplicate the interrupt handling
code.
A problem arises when a third-party COM driver is being used. A number of
third-party COM drivers are replacements for Microsoft's COMM.DRV, but they
may not have replaced Microsoft's VCD. For these third-party COM drivers,
it is still necessary for Microsoft's VCD to handle the interrupts. To
provide this compatibility and still shrink the VCD code for a default
installation, Microsoft made the VCD configurable.
If "COMMDRV30=TRUE" is added to the [386Enh] section of the SYSTEM.INI
file, then the VCD will allocate memory and include the code to handle
interrupts for the Windows 3.0-compatible COM driver.
This switch applies only to enhanced mode Windows. It does not affect
MS-DOS applications or the performance of the Windows 3.1 COMM.DRV.
KBCategory: kbenv
KBSubcategory: win31 wincomm windrvr
| Modification Type: | Major | Last Reviewed: | 10/13/2003 |
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| Keywords: | KB82789 |
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