Sorry to occupy your precious time. Recently,I have a project carrying out the program of FMM on DSP.But when I use the CCS 2.20 to carry out the simple C code such as hello.c ,it can't build.Compiling window demonstrate the following : Error, Don't know how to build file "D:\ccs-test\examples\hello world\main.c" Compile Complete, 1 Errors, 0 Warnings, 0 Remarks. But when compiling and building the complicated program,it's strange to pass. Why??