Actually DOS is not really "gone". One has to understand the architecture of XP, Win2K as well as WinNT4. They are much the same. DOS as well as the 16 bit runtime run as "sub-systems". This has been true with XP and its predecessors. Chances are that DOS will never go away because there are too many things tied to the DOS sub-system that makes it almost impossible to get rid of.
As for accessing things like modems, soundcards or other devices all depends on how the sub-system has been designed to access them. But, for now, with the risk of getting into a long boring diatribe on this, lets just say it's not worth getting into.... However, the older DOS programs should be able to access these devices. 73; Kurt - W2MW XP is an evolution of WIN2000 and WIN98 and doesn't "really" have DOS. XP and WIn2000 have a Command Prompt (C:> prompt), and certain old DOS commands are still available, but I doubt you could count on "old" ham programs that utilize anything very special, e.g. soundcard, to work under XP. This is why RITTY/K6STI won't run under WIN2000 Command Prompt. If you're still tied into DOS, stick with WIN98. Someday you will want to move up though, so be thinking about saying bye bye to DOS! ;-)

