Microsoft KB Archive/170083

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HOWTO: Set Modem Lines Initial States in Win95 SERIAL.VXD


The information in this article applies to:

  • Microsoft Win32 Device Driver Kit (DDK) Windows 95


The default Win95 COMM driver is a VCOMM port driver. Sometimes, you may need to set different default initial serial ports for the modem lines.


Even though some modem lines can be set differently after the port is opened, this may still cause a glitch in sensitive hardware. Note that boot- up Plug and Play activation of modem lines is a different issue for legacy or special hardware. For additional information, please see the following article in the Microsoft Knowledge Base:

Q153385 HOWTO: Disable Plug and Play for a Serial Hardware Device

The source code for SERIAL.VXD is given on the Windows 95 DDK in the COMM\SAMPLES\SERIAL subdirectory. To see where the modem lines are set, look after the label PO_Done: add modifying code lines after "or al,ACE_OUT2" in SERFUNC.ASM before it "out"puts it.

Windows 95 DDK 32-bit Assembly Language understanding required.

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Bill Stuart, Microsoft Corporation

Keywords :
Issue type : kbhowto
Technology : kbAudDeveloper kbWin95search kbWinDDKSearch kbWin32sSearch kbWin32DDK95 kbWin32DDKSearch

Last Reviewed: March 5, 1999
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