CodeView for Windows (Cvw.exe), which is included with Microsoft MASM version 6.11 and 16-bit editions of Microsoft Visual C++, does not run in the Microsoft Windows NT operating systems.

In Microsoft Windows NT, you may get the following error message even though the Cvw1.386 file has an entry in System.ini file: CodeView for Windows will run in Windows 95 and 98; however, you may get the following error messages: -and/or-

If you get the first message, then the application has installed a callback that causes notifications to be issued, calling OutputDebugString() for example.

For additional information, please see the following article in the Microsoft Knowledge Base: For the second error message, you may have loaded Emm386.exe in the Config.sys file. Reboot the machine after removing the line loading Emm386.exe by typing REM before device. Or, reboot after increasing memory when Emm386.exe is loaded, adding the RAM command as shown below:

This behavior is by design.

You can use CodeView (Cv.exe) for MS-DOS in Microsoft Windows 95 and Microsoft Windows NT for debugging MS-DOS applications.

Usually MASM version 6.11 code is written as an MS-DOS .exe file and CodeView for MS-DOS (Cv.exe) can be used to debug this type of application. Rarely do programmers write Windows applications in MASM.

Windows applications written in MASM can be debugged using the Visual C++ integrated debugger (use version 1.52 if you are writing a 16-bit application, or use version 4.0 or later if you are writing a 32-bit application). Create a dummy project, using the same name and project directory as the MASM .exe file, in the Visual C++ IDE. Start the debugger and ignore all the messages about the project build.

Note that the Programmers Work Bench (PWB) used for developing MASM programs works in both Windows 95 and Windows NT. It is advisable that you run the New-vars.bat file in an MS-DOS window from the \Binr folder of the MASM installation before using PWB.