Date: Wed, 30 Aug 1995 16:16:01 -0500 (CDT)
From: ALAN L HIGHTOWER <alh AT engr DOT engr DOT uark DOT edu>
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: Real and Protected mode drivers?



On Tue, 29 Aug 1995 tevans AT fastlane DOT net wrote:

> Hi Eli,
> 
> > I don't think that you should worry about efficiency for mouse and 
> > keyboard: how many interrupts can a 1200-baud serial device and a 
> > keyboard cause?  So in DPMI mode you can safely install a PM handler 
> > alone, IMHO.

> I just want to clarify this so I understand better.  So, even if I 
> installed a real mode handler under a DOS DPMI server, it would
> never be called and wouldn't be more effecient?
> 
> The reason I'm asking is that down the line I also need to write an
> interrupt routine for a modem and ethernet cards.

Under DPMI, real mode interrupt requests get deflected to protected mode, 
thus the p-mode handler catches them both.  Installing a real mode handler
would catch the RM interrupts before the deflection occured, resulting in
a slight speed increase.

Lynx - coder / IncanTationS