Regarding an MS-DOS port, I once received the following mail: You asked for an ftp sight for the DOS port of SWI-pl. A port of the 1.5.0. can be found at the following ftp-sight: rs3.hrz.th-darmstadt.de /pub/machines/ms-dos/386/swi-prolog I don't know the memory requirements, but I do know that it requires to run in true 386-mode, f.ex. it can't be run under MS-windows. I believe that the DOS version lacks some functionality that is found in the Unix versions. But I haven't really tested the DOS version that much since I don't use the DOS version anymore. I prefer using Linux, X11emacs and SWI-pl which I think is superior to the DOS environment. --- Jan