The compiler is suitable for parts with as little as 1K program memory and 64 bytes RAM. The kernel code occupies 100-500 bytes, and it's recommended to reserve about 24 bytes for the stacks. At this size, only a bare minimum of Forth words are supported. There is no resident interpreter or compiler.
The assemblers, compiler, and kernel are written in Forth and are all very simple. The user is encouraged to make modifications as see fit.