I compiled one routine (m15gui.c) belonging to a big Monte Carlo package with compiler option -g to build the symbol table just for this routine only. It sounds confusing. But what I did is to append the routine source file "m15gui.c" to the GNUmakefile as follows: SRCS := marsmain.f m1505.f m5gui.c Then I replaced the original compiler and linker options: CFLAGS := -O3 -xarch=v8 LDFLAGS := -fast -xarch=v8 -xlang=f77 -L/usr/openwin/lib with the following: CFLAGS := -g -xarch=v8 LDFLAGS := -fast -g -C -xs -xildoff -xarch=v8 -xlang=f77 -L/usr/openwin/lib It compiled fine. The program I wish to debug resides in /home/mauede/mars15/dev When I launch DDD and open the program a message window pops up. The title is: DDD No Source The message reads as follows: /home/mauede/mars15/dev/sysdeps/i386/elf/start.S: no such file or directory OK Help Please, notice that my laptop is 64-bit and the message above sounds likeit's searching for some 32-bit feature ... ? I'm debugging a 32-bit code....... Are the DDD settings to be changed ? If this is the case then how shall I change them ??? Thank you so much for your help, -- Maura E.M