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From: altman@sbstaff2.cs.sunysb.edu (Jeff Altman)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Why use MS-window ?
Message-ID: <9609@sbcs.sunysb.edu>
Date: 1 Jun 90 08:09:20 GMT
References: <4aba851b.20b6d@apollo.HP.COM>
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Organization: State University of New York at Stony Brook
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One way to allow communication packages to run in background
to perform file transfers is to not actually let the applications
receive the interrupts from the UART.  What you do is capture 
the interrupts and then when the Comm Package is given its chance
to use the CPU re-echo the interrupts to the Comm Package, thereby 
making it think that it is actually receiving the characters when 
they were received.  

I'm not sure if this is how it is done, somebody please correct me
if I am wrong.

I should mention however that Win 3.0 does not multitask DOS Apps 
well enoungh on a 16 MHz 386sx machine with 4MB to allow MS-Kermit 
to download files in background.  Data transfers are aborted.
But this might be caused by the Kermit Protocols requirement that
once a packet is started to be received there can not be any pauses
in the receipt of the packet of more than 1 sec.

Whereas, Windows based communication packages such as Crosstalk for 
Windows do a wonderful job of performing file transfers in background.

- Jeff (jaltman@ccmail.sunysb.edu)