GC> device.  With OS/2, I'm not so sure.  Because of the 
 GC> greater protection OS/2 affords the entire system, 
 GC> will I be required to write a device driver to access 
 GC> the CPU ring that allows direct port manipulation?

You CAN do "in" and "out" from a user program (ring
2/3),  but not anything else (DMA, IRQs).   Also,  a user program doing
in/out do a very busy device (high throughput) is not a good idea.

In the best situation,  you should write a device driver to talk to the
hardware,  but this is hard for the first timer,  and I can understand why
you might opt for the user program solution.

Note that the segments that do the in/out have to be marked as
"IOPL" in your linker *.def file.



--- Maximus/2 2.01