4tH is a Forth compiler with a little difference. Instead of the standard Forth engine it features a conventional compiler. 4tH is a very small compiler that can create bytecode, C-embeddable bytecode, standalone executables, but also works fine as a scripting language. It supports about 95% of the ANS Forth CORE wordset and features conditional compilation, pipes, files, assertions, forward declarations, enumerations, structures, suspended execution, recursion, include files, etc. It comes with an RPN calculator, line editor, preprocessor, compiler, decompiler, C-source generator, a virtual machine, and a multitasking environment.
bigFORTH is a native code Forth. It was originally developed on the Atari ST for the Motorola 68k processor and was recently ported to Intel 386, running under a DOS extender (GO32). bigFORTH is available for Linux and Windows 95/98/NT in pre-beta-test. This version is available under GPL. The most striking new feature is the graphical user interface MINOS and the form editor Theseus. MINOS is a graphic user interface (GUI) for X, written for bigFORTH-Linux and bigFORTH-Win32. It includes a rapid GUI developement editor (Theseus).