I had to make a few patches for pgptools and magic money to compile on a dos system with microsoft c 6.0. #include <mem.h> and #include <io.h> do not work with this compiler. I added #ifdef __TURBOC__ around these includes in mm.c, s.c, c.c, and ptd.c. In pgpmem.c, this system has malloc.h but not alloc.h. Change the #ifdef MSDOS to #ifdef __TURBOC__. With these changes it worked.