Too add to what roboman as put, retroforth is a type of forth, it was made by one of our founding members CRC, the big problem was he type to port retroforth when DexOS was at a very early stage of development, which did not work out good, as we where change things around a lot, as new stuff was being added.
I think he started porting before we even had a floppy driver.
Theres also been some great work on a port of Reda4 forth by redaman
http://www.geocities.com/redaforth/
I will try and find the port and post it.