CPMBASE.M80 is the current, working source file for KERMIT-80.  All the
CPM*.HEX files are generated from it, by setting the appropriate conditional
assembly variables to TRUE or FALSE and assembling -- set the one you want to
TRUE, all the others to FALSE.  Minor exception: some systems, like the MDI,
have terminal emulation support for more than one terminal, so you must also
select one of them or else you will get undefined symbols.