Forth Variants

Direct threaded code.

In this model, the code field contains machine code instead of a pointer to machine code This is somewhat faster, but typically costs extra bytes for some classes of words. It is most prevalent on 32-bit systems.

Subroutine-threaded code

In this model, the compiler places a jump-to-subroutine instruction with the destination address in-line. This technique costs extra bytes for each compiled reference on a 16-bit system. It is often slower than direct-threaded code, but it is an enabling technique to allow the progression to native code generation.