Every once in a while it would be nice to program a PC to put out a certain waveform one of the printer port pins, or to send something out the serial port with some sort of reasonably precise timing.

Back in the good old days, this was easy; any program you wrote, once running, could take over the entire machine and do anything it wanted. The gory details of the hardware were simple and well documented. There was no protection mechanism to prevent you from banging directly on the hardware. There was no such thing as having your program preempted periodically by the OS.

Is it possible to realize such an environment on a modern PC without having all of its user-friendly, plug-and-play, configure-itself hardware get in the way?

Will plain old DOS run on modern hardware the way it did once upon a time?

Is there some non-protected version of Linux that will allow the kind of thing I'm talking about?

Would it be reasonably feasible to make a modern PC boot directly into a user-written program rather than into Windows?

-- Russ