Date: Thu, 12 Oct 1995 10:53:12 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Sam Vincent <svincent AT zippy DOT sonoma DOT edu>
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: Missing interrupts???


On 11 Oct 1995, Sam Vincent wrote:

> I miss characters which I should be receiving from the modem...
> I set the serial port at 57600..  connect at 26400..  and receive only about
> half to 3/4 of the characters that are sent to my modem..

If you use the wrapper library functions, then this interrupt frequency 
seems too high for your CPU to keep up.  What CPU do you have?  If it's 
DX-33 ot lower, then you might have to switch to assembly interrupt 
routines which don't use the wrappers.  But before that, check if you 
aren't using EMM386.  Somebody told us that he went from 2000 interrupts 
per second to 6000 just by tossing EMM386.

> I'm using V2 beta 2 (I assume beta 3 isn't THAT much different..)
> Thus, in dpmi, all interrupts should be reflected to protected mode
> and thus to my handler..

That's correct.  But the reflection is very heavy: on a DX-33 it eats up
about 3000 CPU cycles!  And the wrapper functions eat up some more.