There are 2 ways to make netCDF work in compaq visual fortran 6 on windows machines.
Both are included in the workspace  file (*.dsw) as separate projects (*.dsp).
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I ) Using binaries from unidata and compiling the f90 layer and typesizes yourselves. 
See http://publicwiki.deltares.nl/display/NETCDF/netcdf+access+with+compaq+visual+fortran
This requires tweaking compiler options to your *.dsp file to deal with C-fortran name mangling options correctly.
This is what we recommend as it relies solely on unidata binaries and fully known dsp files.
We made this work for debug mode only currently, based in the working example in the Xbeach code
$HeadURL$
$Revision$
Libraries needed to built netcdf support (based on 4.0.1, see http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#windows_netcdf4).
NetCDF is linked dynamically, therefore you need to have the dll's next to the your *.exe (or in windows\system32 ).
The required dll's are netcdf, hdf5, szip, because netcdf is based on hdf. 
The PG version is based on the 
* lowercase (/names:lowercase)           
* underscore after (/assume:underscore)         
* string length after args (/iface:nomixed_str_len_arg)
  convention for external procedures (needed to link).
Additional keywords are:  
* Specify additional settings to use pre-compiler options to optionally 
  exlude netcdf code upon compilation (/fpp /define:"DLL_NETCDF" /define:"USENETCDF").
  Using /fpp This results in intermediate files (*.i90). Example:
  +----------------------------------
  |module ncoutput_module
  |#ifdef HAVE_NETCDF
  |#define NC_ERROR_CHECK=if (status) write(*,*) nf90_message(status)
  |use netcdf
  |status = nf90_create(...
  |NC_ERROR_CHECK
  |status = nf90_addvar(...
  |status = nf90_putvar(...
  |#endif
  +----------------------------------
* Do not use any settings to change fortran datatypes, as it will result in a crash when interfacing netcdf.dll (/real_size:64)

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II) using only dlls from unidata and a pre-compiled f90 layer and typesizes.
In the example below someone managed to compile these libraries to work as includes.
This is what we DO NOT recommend as it relies not only on unidata binaries, but also on binaries of unknown origin.

 1) download from http://www.whigg.ac.cn/yanhm/fortran.htm
 
    +----------------------------------
    | New:  Pre-built NetCDF 3.6.1 Beta1 Win32 Fortran library for IVF and CVF (1.17Mb)
    | 
    | New: Add Fortran90 interface to NetCDF 3.6.1 beta1 Win32 version (Dec 12, 2007)
    | Bug fixed for CVF6.5
    | Bug fixed for IVF9.1.032, IVF10.*
    | Release Date: Dec 12, 2007.
    | This Win32 version can be used in both CVF6.* and IVF9.*, IVF10.* compiler under Windows2000/XP.
    +----------------------------------
 
    Pre-built NetCDF 3.6.1 Beta1 Win32 Fortran library for IVF and CVF (1.17Mb)
    File is called: NetCDF3.6.1Beta1.Win32.for.CVF.IVF.rar

 2) From NetCDF3.6.1Beta1.Win32.for.CVF.IVF.rar
    get \F90\netcdf_test.f90
    and open it in Compaq Visual Fortran. Compile it so it asks for 
    "This build command requires an active project. Would you like to create a default project workspace?"
    Click yes so that it creates an accompanying project/workspace.

 3) Compile it so the Debug and Release directories appear, and save all (workspace *.dsw, project *.dsp)

 4) After Debug and Release appeared put there from NetCDF3.6.1Beta1.Win32.for.CVF.IVF.rar:

    \F90\CVF\include\netcdf90.mod
    \F90\CVF\include\typesizes.mod
    \F90\CVF\lib\netcdf90.lib
    \lib\netcdf.lib
    \lib\netcdfs.lib (this seems not to be essential)
    \include\netcdf.inc
    \bin\netcdf.dll
    
    (in total 7 files: 3 *.lib, 2 *.mod, 1 *.inc, 1 *.dll to Debug and Release)
    
 5) remove the include line from code netcdf_test.f90

 6) add the 3 *.lib to menu item: 
    Project > settings > tab:link > box:object/libray modules so that that box looks like:
    kernel32.lib ... *.lib ... Debug/netcdf.lib Debug/netcdfs.lib Debug/netcdf90.lib

 7) Compile again

 8) Resulting executable should be OK despite the following warning

    +----------------------------------
    | --------------------Configuration: netcdf_test - Win32 Debug--------------------
    | Compiling Fortran...
    | d:\checkouts\openearthtools\fortran\io\netcdf\win32\visual_fortran_6\netcdf_test.f90
    | Linking...
    | LINK : warning LNK4098: defaultlib "libc.lib" conflicts with use of other libs; use /NODEFAULTLIB:library
    | 
    | netcdf_test.exe - 0 error(s), 1 warning(s)
    +----------------------------------

 9) run the executable netcdf_test.exe (this will only work when the netcdf.dll is in the same directory or in PATH)

10) the file example.nc should appear