Re: IO-PORTS

[tmoran@acm.org]

> What operating system are you using? Since you say "COM1", it's
> probably either DOS or Windows.
>...
> But this does not "write directly to the IO port". You can't do that
> in Windows!
  If you really want to write directly you'll need to use the CPU's IO
instructions.  Look at your compiler's docs for their library routines
for that.  If your compiler lacks such a library, you'll have to use
Machine Code Insertions.  IIRC you can access the COM ports directly in
Windows 95 - from the "DOS box" at the least.  Windows may emulate the
IO instructions so speed might be a problem.  To get *useful* access
under Windows you need to write a Windows Device Driver.