1. Checkout the latest cfitsio from the repository and make sure you're setup to run Borland C++ or VC++. You can't make a proper dll/def file pair that will work with both Borland and VC++ using VC++ (I know, you're shocked :) and someone had problems using a Borland library with VC++, so you've got to build separate libraries for Borland and VC++ users. 2. 'del make.com' or you can't type 'make' without trying to run this old VMS relic. (relevant only for Borland) 3. 'make -f makefile.bc' for Borland and 'nmake -f makefile.vcc' for VC++. This should generate cfitsio.def and cfitsio.dll, along the way it will make windumpexts.exe to write the cfitsio.def file. 4. To wrap up the distribution, put the following files into a zip file. You may want to rename Readme.win32 to README before putting it in the distribution for consistency with past releases but whatever. cfitsio.def cfitsio.dll cfitsio.lib fitsio.h longnam.h Readme.win32 -> README testprog.c testprog.std testprog.tpt 5. Unzip your distribution to a temporary directory and build and run the test program with VC++ and Borland to be sure it works. VC++: cl testprog.c cfitsio.lib BC++: bcc32 -f testprog.c cfitsio.lib