For the moment, let's focus on Red architecture :
|Red architecture overview|
At the moment, Red/System Compiler and Linker are written in Rebol.
Let's see the Bootstrapping for Red :
1/ Writting Red/System compiler in Rebol
2/ Writting Red/System linker in Rebol
3/ Writting Red runtime in Red/System
4/ Writting Red static compiler in Rebol
5/ Writting Red standard library in Red
6/ Rewritting Red/System compiler in Red
7/ Rewrittng Red static compiler in Red
8/ Writting a Red JIT compiler in Red
For more information about bootstrapping and chicken and egg problem, you can read article on Wikipedia.
Target Operating Systems are : IA-32, ARM, x64, JVM, CLR
For the moment, the effort are concentrated on IA-32. More information on Wikipedia.