OSDev.org

Is it possible to develop a operating system without using the GNU software???

Yes.

Pretty odd question. It's possible to develop an operating system with just a hex editor if you really want to. The question then becomes how many tools do you want to create before you get down to the business of making an OS.

If you're looking for a set of programs that do what the GNU toolchain does without actually being the GNU toolchain then it's certainly possible, it just takes a little more work to track them down. However the further you get away from the GNU toolchain the less support you're likely to get with any problems (A lot of people work with those GNU tools).

If you mean GCC by GNU Software, it is possible to use other compilers and linkers but it isn't recommended since GCC is more configurable then most so is better suited to OS Development.