I was speaking of Microsoft's Visual Studio. I have an old version. I guess you are referring to a GNU type of c# compiler. First the reason I wanted to do a c# project was because I need some wheels up time with the development environment and its library's. I can still do the project; however, I will not have an RS232 serial interface. I'll use UDP and have an Arm 7 or 9 read the serial and send it via UDP. c# is a Microsoft creature and doing development outside of its development environment never occurred to me. I would first think of using java. In fact I'm a little surprised that a GNU type of c# compiler exist. I would have thought Microsoft would have copywrited it like intel did to the 8085's assembly language thus the Z80's back in the day.
Thanks for the input. I'll look into a free one though using gdb to debug it doesn't sound like fun.