4IM
4IM is a Forth system for the PC. It is a very simple, compact and efficient Forth. It can boot off a floppy in a stand-alone version or it can run under DOS.
4IM can be modified and recompiled from source in a glance independantly of any external software thanks to it's block editor and it's assembler. Other applications, toolboxes and libraries are provided to make it comfortable, modular, and powerful: multithread support, floppy disk caching, disassembler/debugger, blockfile management tools and many more. "4IM" [ cat-tree-M] sounds like the french word for "fourth".
HOMEPAGE: http://4im.atspace.com/