CW Decoder latest release from August 2008 was probably built with Windows XP in mind. I managed to get it working. I chose this particular one because it does rather well with decoding CW via Virtual Audio Cable Lite (free version of VAC limited to 1 virtual cable). I find it works better than FLDigi's built in decoder. Source radio is the RSP1b/SDRuno.
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The trick to doing this is run its setup in compatibility mode for Windows XP SP3. It will first unzip 2 files. An inf file and the setup.exe file.
The first thing to do is create a new folder in C:\
It should be like this C:\CWDecoder.
Run the CW Decoder.exe and point it to C:\CWDecoder
After that there are two files in C:\CWDecoder
In the C:\CWDecoder run setup.exe in compatibility mode for Windows XP SP3
Point the installer to C:\CWDecoder
You should now have
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To run CW Decoder it must be in compatibility mode.
Right click on CWDecoderXP.exe then select the compatibility tab then match these settings then click Apply and exit
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The installer won't write a shortcut to the desktop. You will have to make one.
I found it at DXZone as a direct download. You will have to do the search. It may even be linked in RR Wiki. I haven't looked on the Wiki. I usually sleuth these things on Google then go from there.
I hope this is found useful to some willing to try it. It is rather dated but it is very effective software for its age.
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The trick to doing this is run its setup in compatibility mode for Windows XP SP3. It will first unzip 2 files. An inf file and the setup.exe file.
The first thing to do is create a new folder in C:\
It should be like this C:\CWDecoder.
Run the CW Decoder.exe and point it to C:\CWDecoder
After that there are two files in C:\CWDecoder
In the C:\CWDecoder run setup.exe in compatibility mode for Windows XP SP3
Point the installer to C:\CWDecoder
You should now have

To run CW Decoder it must be in compatibility mode.
Right click on CWDecoderXP.exe then select the compatibility tab then match these settings then click Apply and exit

The installer won't write a shortcut to the desktop. You will have to make one.
I found it at DXZone as a direct download. You will have to do the search. It may even be linked in RR Wiki. I haven't looked on the Wiki. I usually sleuth these things on Google then go from there.
I hope this is found useful to some willing to try it. It is rather dated but it is very effective software for its age.