AM> If you can only access a comport by using the DOS method (ie. doing
 AM> everything yourself) than I can't really help you. 
It's a good thing that he doesn't need your help then.  (-:
In OS/2 a COM device can be opened and treated just like a file.  In DOS one 
can do the same, but the device driver doesn't support interrupt driven use 
of the UARTs, which causes problems.  OS/2, more specifically the COM.SYS 
device driver, *does* use interrupts, however.  Serial comms in OS/2 using 
the device-as-file approach is entirely interrupt driven.
 ¯ JdeBP ®
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