Hi gcc experts, I try to compile a sample .c file that communicates with the GPIB interface (see attached c file) by using GCC type of compilers, such as cygwin, Dev-Cpp, MinGW, and C-Free4. Then I got the same sort of error messages - the low level drivers were not found, see the log below: gcc.exe "C:\Program Files\Agilent\IO Libraries Suite\ProgrammingSamples\C\VISA\idn.c" -o "C:\Program Files\Agilent\IO Libraries Suite\ProgrammingSamples\C\VISA\idn.exe" -ansi -I"C:\Program Files\VXIPNP\WINNT\include" -L"C:\Program Files\VXIPNP\WINNT\lib\msc" C:\DOCUME~1\duanwang\LOCALS~1\Temp/ccOycaaa.o(.text+0x59):idn.c: undefined reference to `viOpenDefaultRM@4' C:\DOCUME~1\duanwang\LOCALS~1\Temp/ccOycaaa.o(.text+0x86):idn.c: undefined reference to `viOpen@20' C:\DOCUME~1\duanwang\LOCALS~1\Temp/ccOycaaa.o(.text+0x9c):idn.c: undefined reference to `viPrintf' C:\DOCUME~1\duanwang\LOCALS~1\Temp/ccOycaaa.o(.text+0xb9):idn.c: undefined reference to `viScanf' C:\DOCUME~1\duanwang\LOCALS~1\Temp/ccOycaaa.o(.text+0xda):idn.c: undefined reference to `viClose@4' C:\DOCUME~1\duanwang\LOCALS~1\Temp/ccOycaaa.o(.text+0xe8):idn.c: undefined reference to `viClose@4' collect2: ld returned 1 exit status The low level drivers, such as viPrintf and viScanf are in the file of visa32.lib that is seated in the directory of ...\lib\msc. I mean the drivers are sit there but he compiler complains that the drivers were not found. And the same error happens either in windows application or in DOS window. Is there something wrong? Please advise. What I expect is to produce an .exe file that will talk to the instrument that is connected with the pc with a GPIB interface. Thanks, Duan Wang Alcatel-Lucent 978-952-7057