The KA9Q Network Operating System ("KA9Q NOS") is one of the
most flexible MS-DOS applications you could use, offering an
assortment of TCP/IP clients and servers. Since the code is
small, and entirely memory-resident, it can be run off a floppy.
(Some servers, like smtp and pop, really want a hard drive.)
Unfortunately, it calls upon MS-DOS for file I/O...
Phil Karn licensed the KA9Q code to Telebit for use in their
(Telebit no longer exists as such, having purchased by a German
firm a little over two years ago.)