Where are design objectives located? It looks like after dos5 the read-only files of msdos.sys and io.sys were edited to support a shell. (I got this info from a.i. so may have broken gnu license rules if I was to help with programming, idk) sad for me.) This looks fun to try. Has anyone tried? It appears the freedos team, others may not care. Freedos at least required or required I not look at MSDos proprietary code to work on freedos. Haven't looked at guidelines for dosbox yet, looks like the code is on sourceforge and uses svn. Another project is called: DOSemu: http://www.dosemu.org/ and has a kernel.