LEGO MINDSTORMS Robots Manual page 173

Figure 10-1.
legOS software architecture
Development Tools
You'll need some heavy-duty tools to work with legOS. (There is another possibility, as described in the sidebar, ''An Innovative Alternative.") The good news is that the tools are free. The basic
tool you need is a cross compiler, a tool that runs on one platform but produces executable files for another. In this case, you want a cross compiler that runs on your PC and produces firmware for
the RCX.
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legOS is built using egcs, the open-source successor to the GNU gcc compiler. To build legOS, you'll also need GNU's binutils package. These tools are present on most Linux systems,
but they must be reconfigured to support cross-compilation for the RCX. I'll explain this process soon.
If you're not running Linux, don't despair. On a Unix-like operating system, you can probably build egcs and binutils yourself, or find someone who has binaries for your platform. See the
"Online Resources" section later in this chapter for information on obtaining egcs and binutils.
Cygwin
What if you're not running Linux or a Unix-like operating system? If you have Windows instead, there is a way to make Windows act like Linux. The Cygwin package from Cygnus Solutions is a
port of many GNU tools to Windows 95, 98, and NT. Like lots of GNU stuff, it's a little bulky. A full download is about 13 MB, compressed. If you're a Linux enthusiast trapped in a Microsoft
world, though, you'll definitely want to check this out. (The "Online Resources" section has more information on obtaining Cygwin.)
Setting Up egcs
To compile legOS, you're going to need to configure egcs as a cross compiler for the RCX. There are two ways to do this:
1. You can recompile egcs itself to make it into a cross compiler.
2. You can download someone else's binary version of the egcs cross compiler.
Obviously, the second option is a lot easier, if you can find somebody who's created the cross compiler for your particular platform. The "Online Resources" section at the end of this chapter lists
web sites that contain instructions for recompiling egcs as well as the locations of popular binaries of the cross compiler.
Oh, and Perl Too